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94. Education and Training Services

94. Education and Training Services (7)

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94. Education and Training Services

Chapter Editor: Michael McCann


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Tables and Figures

E. Gelpi
 
Michael McCann
 
Gary Gibson
 
Susan Magor
 
Ted Rickard
 
Steven D. Stellman and Joshua E. Muscat
 
Susan Magor

Tables 

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1. Diseases affecting day-care workers & teachers
2. Hazards & precautions for particular classes
3. Summary of hazards in colleges & universities

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95. Emergency and Security Services

95. Emergency and Security Services (9)

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95. Emergency and Security Services

Chapter Editor: Tee L. Guidotti


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Tables and Figures

Tee L. Guidotti
 
Alan D. Jones
 
Tee L. Guidotti
 
Jeremy Brown
 
Manfred Fischer
 
Joel C. Gaydos, Richard J. Thomas,David M. Sack and Relford Patterson
 
Timothy J. Ungs
 
John D. Meyer
 
M. Joseph Fedoruk

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1. Recommendations & criteria for compensation

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96. Entertainment and the Arts

96. Entertainment and the Arts (31)

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96. Entertainment and the Arts

Chapter Editor: Michael McCann


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Tables and Figures

Arts and Crafts

Michael McCann 
Jack W. Snyder
Giuseppe Battista
David Richardson
Angela Babin
William E. Irwin
Gail Coningsby Barazani
Monona Rossol
Michael McCann
Tsun-Jen Cheng and Jung-Der Wang
Stephanie Knopp

Performing and Media Arts 

Itzhak Siev-Ner 
 
     Susan Harman
John P. Chong
Anat Keidar
    
     Jacqueline Nubé
Sandra Karen Richman
Clëes W. Englund
     Michael McCann
Michael McCann
Nancy Clark
Aidan White

Entertainment

Kathryn A. Makos
Ken Sims
Paul V. Lynch
William Avery
Michael McCann
Gordon Huie, Peter J. Bruno and W. Norman Scott
Priscilla Alexander
Angela Babin
Michael McCann
 

Tables

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1. Precautions associated with hazards
2. Hazards of art techniques
3. Hazards of common stones
4. Main risks associated with sculpture material
5. Description of fibre & textile crafts
6. Description of fibre & textile processes
7. Ingredients of ceramic bodies & glazes
8. Hazards & precautions of collection management
9. Hazards of collection objects

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97. Health Care Facilities and Services

97. Health Care Facilities and Services (25)

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97. Health Care Facilities and Services

Chapter Editor: Annelee Yassi


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Tables and Figures

Health Care: Its Nature and Its Occupational Health Problems
Annalee Yassi and Leon J. Warshaw

Social Services
Susan Nobel

Home Care Workers: The New York City Experience
Lenora Colbert

Occupational Health and Safety Practice: The Russian Experience
Valery P. Kaptsov and Lyudmila P. Korotich

Ergonomics and Health Care

Hospital Ergonomics: A Review
Madeleine R. Estryn-Béhar

Strain in Health Care Work
Madeleine R. Estryn-Béhar

     Case Study: Human Error and Critical Tasks: Approaches for Improved System Performance

Work Schedules and Night Work in Health Care
Madeleine R. Estryn-Béhar

The Physical Environment and Health Care

Exposure to Physical Agents
Robert M. Lewy

Ergonomics of the Physical Work Environment
Madeleine R. Estryn-Béhar

Prevention and Management of Back Pain in Nurses
Ulrich Stössel

     Case Study: Treatment of Back Pain
     Leon J. Warshaw

Health Care Workers and Infectious Disease

Overview of Infectious Diseases
Friedrich Hofmann

Prevention of Occupational Transmission of Bloodborne Pathogens
Linda S. Martin, Robert J. Mullan and David M. Bell 

Tuberculosis Prevention, Control and Surveillance
Robert  J. Mullan

Chemicals in the Health Care Environment

Overview of Chemical Hazards in Health Care
Jeanne Mager Stellman 

Managing Chemical Hazards in Hospitals
Annalee Yassi

Waste Anaesthetic Gases
Xavier Guardino Solá

Health Care Workers and Latex Allergy
Leon J. Warshaw

The Hospital Environment

Buildings for Health Care Facilities
Cesare Catananti, Gianfranco Damiani and Giovanni Capelli

Hospitals: Environmental and Public Health Issues
M.P. Arias

Hospital Waste Management
M.P. Arias

Managing Hazardous Waste Disposal Under ISO 14000
Jerry Spiegel and John Reimer

Tables

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1. Examples of health care functions
2. 1995 integrated sound levels
3. Ergonomic noise reduction options
4. Total number of injuries (one hospital)
5. Distribution of nurses’ time
6. Number of separate nursing tasks
7. Distribution of nurses' time
8. Cognitive & affective strain & burn-out
9. Prevalence of work complaints by shift
10. Congenital abnormalities following rubella
11. Indications for vaccinations
12. Post-exposure prophylaxis
13. US Public Health Service recommendations
14. Chemicals’ categories used in health care
15. Chemicals cited HSDB
16. Properties of inhaled anaesthetics
17. Choice of materials: criteria & variables
18. Ventilation requirements
19. Infectious diseases & Group III wastes
20. HSC EMS documentation hierarchy
21. Role & responsibilities
22. Process inputs
23. List of activities

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98. Hotels and Restaurants

98. Hotels and Restaurants (4)

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98. Hotels and Restaurants

Chapter Editor: Pam Tau Lee


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Pam Tau Lee
 
 
Neil Dalhouse
 
 
Pam Tau Lee
 
 
Leon J. Warshaw
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99. Office and Retail Trades

99. Office and Retail Trades (7)

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99. Office and Retail Trades

Chapter Editor: Jonathan Rosen


Table of Contents

Tables and Figures

The Nature of Office and Clerical Work
Charles Levenstein, Beth Rosenberg and Ninica Howard

Professionals and Managers
Nona McQuay

Offices: A Hazard Summary
Wendy Hord

Bank Teller Safety: The Situation in Germany
Manfred Fischer

Telework
Jamie Tessler

The Retail Industry
Adrienne Markowitz

     Case Study: Outdoor Markets
     John G. Rodwan, Jr.

Tables 

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1. Standard professional jobs
2. Standard clerical jobs
3. Indoor air pollutants in office buildings
4. Labour statistics in the retail industry

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100. Personal and Community Services

100. Personal and Community Services (6)

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100. Personal and Community Services

Chapter Editor: Angela Babin


Table of Contents

Tables and Figures

Indoor Cleaning Services
Karen Messing

Barbering and Cosmetology
Laura Stock and James Cone

Laundries, Garment and Dry Cleaning
Gary S. Earnest, Lynda M. Ewers and Avima M. Ruder

Funeral Services
Mary O. Brophy and Jonathan T. Haney

Domestic Workers
Angela Babin

     Case Study: Environmental Issues
     Michael McCann

Tables

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1. Postures observed during dusting in a hospital
2. Dangerous chemicals used in cleaning

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101. Public and Government Services

101. Public and Government Services (12)

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101. Public and Government Services

Chapter Editor: David LeGrande


Table of Contents

Tables and Figurs

Occupational Health and Safety Hazards in Public and Governmental Services
David LeGrande

     Case Report: Violence and Urban Park Rangers in Ireland
     Daniel Murphy

Inspection Services
Jonathan Rosen

Postal Services
Roxanne Cabral

Telecommunications
David LeGrande

Hazards in Sewage (Waste) Treatment Plants
Mary O. Brophy

Domestic Waste Collection
Madeleine Bourdouxhe

Street Cleaning
J.C. Gunther, Jr.

Sewage Treatment
M. Agamennone

Municipal Recycling Industry
David E. Malter

Waste Disposal Operations
James W. Platner

The Generation and Transport of Hazardous Wastes: Social and Ethical Issues
Colin L. Soskolne

Tables

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1. Hazards of inspection services
2. Hazardous objects found in domestic waste
3. Accidents in domestic waste collection (Canada)
4. Injuries in the recycling industry

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102. Transport Industry and Warehousing

102. Transport Industry and Warehousing (18)

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102. Transport Industry and Warehousing

Chapter Editor: LaMont Byrd


Table of Contents

Tables and Figures

General Profile
LaMont Byrd  

     Case Study: Challenges to Workers’ Health and Safety in the Transportation and Warehousing Industry
     Leon J. Warshaw

Air Transport

Airport and Flight Control Operations
Christine Proctor, Edward A. Olmsted and E. Evrard

     Case Studies of Air Traffic Controllers in the United States and Italy
     Paul A. Landsbergis

Aircraft Maintenance Operations
Buck Cameron

Aircraft Flight Operations
Nancy Garcia and H. Gartmann

Aerospace Medicine: Effects of Gravity, Acceleration and Microgravity in the Aerospace Environment
Relford Patterson and Russell B. Rayman

Helicopters
David L. Huntzinger

Road Transport

Truck and Bus Driving
Bruce A. Millies

Ergonomics of Bus Driving
Alfons Grösbrink and Andreas Mahr

Motor Vehicle Fuelling and Servicing Operations
Richard S. Kraus

     Case Study: Violence in Gasoline Stations
     Leon J. Warshaw

Rail Transport

Rail Operations
Neil McManus

     Case Study: Subways
     George J. McDonald

Water Transport

Water Transportation and the Maritime Industries
Timothy J. Ungs and Michael Adess

Storage

Storage and Transportation of Crude Oil, Natural Gas, Liquid Petroleum Products and Other Chemicals
Richard S. Kraus

Warehousing
John Lund

     Case Study: US NIOSH Studies of Injuries among Grocery Order Selectors

Tables

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1. Bus driver seat measurements
2. Illumination levels for service stations
3. Hazardous conditions & administration
4. Hazardous conditions & maintenance
5. Hazardous conditions & right of way
6. Hazard control in the Railway industry
7. Merchant vessel types
8. Health hazards common across vessel types
9. Notable hazards for specific vessel types
10. Vessel hazard control & risk-reduction
11. Typical approximate combustion properties
12. Comparison of compressed & liquified gas
13. Hazards involving order selectors
14. Job safety analysis: Fork-lift operator
15. Job safety analysis: Order selector

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Thursday, 31 March 2011 17:34

Aircraft Flight Operations

Adapted from the 3rd edition Encyclopaedia article “Aviation - flying personnel” authored by H. Gartmann.

This article deals with the occupational safety and health of the crew members of civil aviation aircraft; see also the articles “Airport and flight control operations”, “Aircraft maintenance operations” and “Helicopters” for additional information.

Technical Crew Members

The technical personnel, or flight crew members, are responsible for the operation of the aircraft. Depending on aircraft type, the technical crew includes the pilot-in-command (PIC), the co-pilot (or first officer), and the flight engineer or a second officer (a pilot).

The PIC (or captain) has the responsibility for the safety of the aircraft, the passengers and the other crew members. The captain is the legal representative of the air carrier and is vested by the air carrier and the national aviation authority with the authority to carry out all actions necessary to fulfil this mandate. The PIC directs all duties on the flight deck and is in command of the entire aircraft.

The co-pilot takes his or her orders directly from the PIC and acts as the captain’s deputy upon delegation or in the latter’s absence. The co-pilot is the primary assistant to the PIC in a flight crew; in newer generation, two-person flight deck operations and in older two-engine aircraft, he or she is the only assistant.

Many older generation aircraft carry a third technical crew member. This person may be a flight engineer or a third pilot (usually called the second officer). The flight engineer, when present, is responsible for the mechanical condition of the aircraft and its equipment. New generation aircraft have automated many of the functions of the flight engineer; in these two-person operations, the pilots perform such duties as a flight engineer might otherwise perform that have not been automated by design.

On certain long-distance flights, the crew may be supplemented by a pilot with the qualifications of the PIC, an additional first officer and, when required, an additional flight engineer.

National and international laws stipulate that aircraft technical personnel may operate aircraft only when in possession of a valid licence issued by the national authority. In order to maintain their licences, technical crew members are given ground school training once every year; they are also tested in a flight simulator (a device that simulates real flight and flight emergency conditions) twice a year and in actual operations at least once a year.

Another condition for the receipt and renewal of a valid licence is a medical examination every 6 months for airline transport and commercial pilots over 40 years old, or every 12 months for commercial pilots under 40 years old and for flight engineers. The minimum requirements for these examinations are specified by the ICAO and by national regulations. A certain number of physicians experienced in aviation medicine may be authorized to provide such examinations by the national authorities concerned. These may include air ministry physicians, airforce flight surgeons, airline medical officers or private practitioners designated by the national authority.

Cabin Crew Members

The cabin crew (or flight attendants) are primarily responsible for passenger safety. Flight attendants perform routine safety duties; in addition, they are responsible for monitoring the aircraft cabin for security and safety hazards. In the event of an emergency, the cabin crew members are responsible for the organization of emergency procedures and for the safe evacuation of the passengers. In flight, cabin crew may need to respond to emergencies such as smoke and fire in the cabin, turbulence, medical trauma, aircraft decompressions, and hijackings or other terrorist threats. In addition to their emergency responsibilities, flight attendants also provide passenger service.

The minimum cabin crew ranges from 1 to 14 flight attendants, depending on the type of aircraft, the aircraft’s passenger capacity and national regulations. Additional staffing requirements may be determined by labour agreements. The cabin crew may be supplemented by a purser or service manager. The cabin crew is usually under the supervision of a lead or “in-charge” flight attendant, who, in turn, is responsible and reports directly to the PIC.

National regulations do not usually stipulate that the cabin crew should hold licences in the same way as the technical crew; however, cabin crew are required by all national regulations to have received appropriate instruction and training in emergency procedures. Periodic medical examinations are not usually required by law, but some air carriers require medical examinations for the purposes of health maintenance.

Hazards and Their Prevention

All air crew members are exposed to a wide variety of stress factors, both physical and psychological, to the hazards of an aircraft accident or other flight incident and to the possible contraction of a number of diseases.

Physical stress

Lack of oxygen, one of the main concerns of aviation medicine in the early days of flying, had until recently become a minor consideration in modern air transport. In the case of a jet aircraft flying at 12,000 m altitude, the equivalent altitude in the pressurized cabin is only 2,300 m and, consequently, symptoms of oxygen deficiency or hypoxia will not normally be encountered in healthy persons. Oxygen deficiency tolerance varies from individual to individual, but for a healthy, non-trained subject the presumed altitude threshold at which the first symptoms of hypoxia occur is 3,000 m.

With the advent of new generation aircraft, however, concerns about cabin air quality have resurfaced. Aircraft cabin air consists of air drawn from compressors in the engine and often also contains recirculated air from within the cabin. The flow rate of outside air within an aircraft cabin can vary from as little as 0.2 m3 per minute per person to 1.42 m3 per minute per person, depending upon aircraft type and age, and depending on location within the cabin. New aircraft use recirculated cabin air to a much greater degree than do older models. This air quality issue is specific to the cabin environment. The flight deck compartment air flow rates are often as high as 4.25 m3 per minute per crew member. These higher air flow rates are provided on the flight deck to meet the cooling requirements of the avionic and electronic equipment.

Complaints of poor cabin air quality from cabin crew and passengers have increased in recent years, prompting some national authorities to investigate. Minimal ventilation rates for aircraft cabins are not defined in national regulations. Actual cabin airflow is seldom measured once an aircraft is put into service, since there is no requirement to do so. Minimal air flow and the use of recirculated air, combined with other issues of air quality, such as the presence of chemical contaminants, micro-organisms, other allergens, tobacco smoke and ozone, require further evaluation and study.

Maintaining a comfortable air temperature in the cabin does not represent a problem in modern aircraft; however, the humidity of this air cannot be raised to a comfortable level, due to the large temperature difference between the aircraft interior and exterior. Consequently, both crew and passengers are exposed to extremely dry air, especially on long-distance flights. Cabin humidity depends on the cabin ventilation rate, passenger load, temperature and pressure. The relative humidity found on aircraft today varies from about 25% to less than 2%. Some passengers and crew members experience discomfort, such as dryness of the eyes, nose and throat, on flights that exceed 3 or 4 hours. There is no conclusive evidence of extensive or serious adverse health effects of low relative humidity on flight personnel. However, precautions should be taken to avoid dehydration; adequate intake of liquids such as water and juices should be sufficient to prevent discomfort.

Motion sickness (dizziness, malaise and vomiting due to the abnormal movements and altitudes of the aircraft) was a problem for civil aviation crews and passengers for many decades; the problem still exists today in the case of small sports aircraft, military aircraft and aerial acrobatics. In modern jet transport aircraft, it is much less serious and occurs less frequently due to higher aircraft speeds and take-off weights, higher cruising altitudes (which take the aircraft above the turbulence zones) and the use of airborne radar (which enables squalls and storms to be located and circumnavigated). Additionally, the lack of motion sickness also may be attributed to the more spacious, open design of today’s aircraft cabin, which provides a greater feeling of security, stability and comfort.

Other physical and chemical hazards

Aircraft noise, while a significant problem for ground personnel, is less serious for the crew members of a modern jet aircraft than was the case with the piston-engined plane. The efficiency of noise control measures such as insulation in modern aircraft have helped to eliminate this hazard in most flight environments. Additionally, improvements in communications equipment have minimized background noise levels from these sources.

Ozone exposure is a known but poorly monitored hazard for air crew and passengers. Ozone is present in the upper atmosphere as a result of the photochemical conversion of oxygen by solar ultraviolet radiation at altitudes used by commercial jet aircraft. The mean ambient ozone concentration increases with increasing latitude and is most prevalent during spring. It can also vary with weather systems, with the result of high ozone plumes descending down to lower altitudes.

Symptoms of ozone exposure include cough, upper airway irritation, tickle in the throat, chest discomfort, substantial pain or soreness, difficulty or pain in taking a deep breath, shortness of breath, wheezing, headache, fatigue, nasal congestion and eye irritation. Most people can detect ozone at 0.02 ppm, and studies have shown that ozone exposure at 0.5 ppm or more causes significant decrements in pulmonary function. The effects of ozone contamination are felt more readily by persons engaged in moderate to heavy activity than those who are at rest or engaged in light activity. Thus flight attendants (who are physically active in flight) have experienced the effects of ozone earlier and more frequently than technical crew or passengers on the same flight when ozone contamination was present.

In one study conducted in the late 1970s by the aviation authority in the United States (Rogers 1980), several flights (mostly at 9,150 to 12,200 m) were monitored for ozone contamination. Eleven per cent of the flights monitored were found to exceed that authority’s permissible ozone concentration limits. Methods of minimizing ozone exposure include choice of routes and altitudes that avoid areas of high ozone concentration and the use of air treatment equipment (usually a catalytic converter). The catalytic converters, however, are subject to contamination and loss of efficiency. Regulations (when they exist) do not require their periodic removal for efficiency testing, nor do they require monitoring of ozone levels in actual flight operations. Crew members, especially cabin crew, have requested that better monitoring and control of ozone contamination be implemented.

Another serious concern for technical and cabin crew members is cosmic radiation, which includes radiation forms that are transmitted through space from the sun and other sources in the universe. Most cosmic radiation that travels through space is absorbed by the earth’s atmosphere; however, the higher the altitude, the less the protection. The earth’s magnetic field also provides some shielding, which is greatest near the equator and decreases at the higher latitudes. Air crew members are exposed to cosmic radiation levels inflight that are higher than those received on the ground.

The amount of radiation exposure depends on the type and the amount of flying; for example, a crew member who flies many hours at high altitudes and high latitudes (e.g., polar routes) will receive the greatest amount of radiation exposure. The civil aviation authority in the United States (the FAA) has estimated that the long-term average cosmic radiation dose for air crew members ranges from 0.025 to 0.93 millisieverts (mSv) per 100 block hours (Friedberg et al. 1992). Based on FAA estimates, a crew member flying 960 block hours per year (or an average of 80 hours/month) would receive an estimated annual radiation dose of between 0.24 and 8.928 mSv. These levels of exposure are lower than the recommended occupational limit of 20 millisieverts per year (5-year average) established by the International Commission on Radiological Protection (ICRP).

The ICRP, however, recommends that occupational exposure to ionizing radiation should not exceed 2 mSv during pregnancy. In addition, the US National Council on Radiation Protection and Measurements (NCRP) recommends that exposure not exceed 0.5 mSv in any month once a pregnancy is known. If a crew member worked an entire month on flights with the highest exposures, the monthly dose rate could exceed the recommended limit. Such a pattern of flying over 5 or 6 months could result in an exposure which also would exceed the recommended pregnancy limit of 2 mSv.

The health effects of low-level radiation exposure over a period of years include cancer, genetic defects and birth defects to a child exposed in the womb. The FAA estimates that the added risk of fatal cancer resulting from exposure to inflight radiation would range from 1 in 1,500 to 1 in 94, depending on the type of routes and number of hours flown; the level of added risk of a serious genetic defect resulting from one parent’s exposure to cosmic radiation ranges from 1 in 220,000 live births to 1 in 4,600 live births; and the risk of mental retardation and childhood cancer in a child exposed in utero to cosmic radiation would range between 1 in 20,000 to 1 in 680, depending upon the type and amount of flying the mother did while pregnant.

The FAA report concludes that “radiation exposure is not likely to be a factor that would limit flying for a non-pregnant crew member” because even the largest amount of radiation received annually by a crew member working as much as 1,000 block hours a year is less than half the ICRP recommended average annual limit. However, for a pregnant crew member, the situation is different. The FAA calculates that a pregnant crew member working 70 block hours per month would exceed the recommended 5-month limit on about one-third of the flights they studied (Friedberg et al. 1992).

It should be stressed that these exposure and risk estimates are not universally accepted. Estimates are dependent upon assumptions about the types and mix of radioactive particles encountered at altitude and the weight or quality factor used to determine dose estimates for some of these forms of radiation. Some scientists believe that the actual radiation hazard to air crew members may be greater than described above. Additional monitoring of the flight environment with reliable instrumentation is needed to more clearly determine the extent of inflight radiation exposure.

Until more is known about exposure levels, air crew members should keep their exposure to all types of radiation as low as possible. With respect to inflight radiation exposure, minimizing the amount of flight time and maximizing the distance from the source of radiation can have a direct effect on the dose received. Reducing monthly and yearly flight time and/or selecting flights which fly at lower altitudes and latitudes will reduce exposure. An air crew member who has the ability to control his or her flight assignments might choose to fly fewer hours per month, to bid for a mix of domestic and international flights or to request leaves periodically. A pregnant air crew member might choose to take a leave for the duration of the pregnancy. Since the first trimester is the most crucial time to guard against radiation exposure, an air crew member planning a pregnancy also may want to consider a leave especially if she is flying long-distance polar routes on a regular basis and has no control over her flight assignments.

Ergonomic problems

The main ergonomic problem for technical crew is the need to work for many hours in a sitting but unsettled position and in a very limited working area. In this position (restrained by lap and shoulder harness), it is necessary to carry out a variety of tasks such as movements of the arms, legs and head in different directions, consulting instruments at a distance of about 1 m above, below, to the front and to the side, scanning the far distance, reading a map or manual at close distance (30 cm), listening through earphones or talking through a microphone. Seating, instrumentation, lighting, cockpit microclimate and radio communications equipment comfort have been and still remain the object of continuous improvement. Today’s modern flight deck, often referred to as the “glass cockpit”, has created yet another challenge with its use of leading-edge technology and automation; maintaining vigilance and situational awareness under these conditions has created new concerns for both the designers of aircraft and the technical personnel who fly them.

Cabin crew have an entirely different set of ergonomic problems. One main problem is that of standing and moving around during flight. During climb and descent, and in turbulence, the cabin crew is required to walk on an inclined floor; in some aircraft the cabin incline may remain at approximately 3% during cruise as well. Also, many cabin floors are designed in a manner that creates a rebound effect while walking, putting an additional stress on the flight attendants who are constantly moving about during a flight. Another important ergonomic problem for flight attendants has been the use of mobile carts. These carts can weigh up to 100 to 140 kg and must be pushed and pulled up and down the length of the cabin. Additionally, the poor design and maintenance of the braking mechanisms on many of these carts have caused an increase in repetitive-strain injuries (RSIs) among flight attendants. Air carriers and cart manufacturers are now taking a more serious look at this equipment, and new designs have resulted in ergonomic improvements. Additional ergonomic problems result from the need to lift and carry heavy or bulky items in restricted spaces or while maintaining uncomfortable body posture.

Workload

The workload for air crew members depends on the task, the ergonomic layout, the hours of work/duty and many other factors. The additional factors affecting the technical crew include:

  • duration of rest time between present and last flight and the duration of sleep time during the rest period
  • the pre-flight briefing and problems encountered during the pre-flight briefing
  • delays preceding departure
  • timing of flights
  • meteorological conditions at the point of departure, en route and at the destination
  • number of flight segments
  • type of equipment being flown
  • quality and quantity of radio communications
  • visibility during descent, glare and protection from the sun
  • turbulence
  • technical problems with the aircraft
  • experience of other crew members
  • air traffic (especially at point of departure and destination)
  • presence of air carrier or national authority personnel for purposes of checking crew competency.

 

Certain of these factors may be equally important for the cabin crew. In addition, the latter are subject to the following specific factors:

  • pressure of time due to short duration of flight, high number of passengers and extensive service requirements
  • extra services demanded by passengers, the character of certain passengers and, occasionally, verbal or physical abuse by passengers
  • passengers requiring special care and attention (e.g., children, the disabled, the elderly, a medical emergency)
  • extent of preparatory work
  • lack of necessary service items (e.g., insufficient meals, beverages and so on) and equipment.

 

The measures taken by air carrier managements and government administrations to keep crew workload within reasonable limits include: improvement and extension of air-traffic control; reasonable limits on hours of duty and requirements for minimum rest provisions; execution of preparatory work by dispatchers, maintenance, catering and cleaning personnel; automation of cockpit equipment and tasks; the standardization of service procedures; adequate staffing; and the provision of efficient and easy-to-handle equipment.

Hours of work

One of the most important factors affecting both technical and cabin crew member occupational health and safety (and certainly the most widely discussed and controversial) is the issue of flight fatigue and recovery. This issue covers the broad spectrum of activity encompassing crew scheduling practices—length of duty periods, amount of flight time (daily, monthly and yearly), reserve or standby duty periods and availability of time for rest both while on flight assignment and at domicile. Circadian rhythms, especially sleep intervals and duration, with all their physiological and psychological implications, are especially significant for air crew members. Time shifts due either to night flights or to east/west or west/east travel across a number of time zones create the greatest problems. Newer generation aircraft, which have the capability of remaining aloft for up to 15 to 16 hours at a time, have exacerbated the conflict between airline schedules and human limitations.

National regulations to limit duty and flight periods and to provide minimum rest limitations exist on a nation by nation basis. In some instances, these regulations have not kept pace with technology or science, nor do they necessarily guarantee flight safety. Until recently there has been little attempt to standardize these regulations. Current attempts at harmonization have given rise to concerns among air crew members that those countries with more protective regulations may be required to accept lower and less adequate standards. In addition to national regulations, many air crew members have been able to negotiate more protective hours of service requirements in their labour agreements. While these negotiated agreements are important, most crew members feel that hours of service standards are essential to their health and safety (and to that of the flying public), and thus minimum standards should be adequately regulated by the national authorities.

Psychological stress

In recent years, aircraft crew have been confronted with a serious mental stress factor: the likelihood of hijacking, bombs and armed attacks on aircraft. Although security measures in civil aviation worldwide have been considerably increased and upgraded, the sophistication of terrorists has likewise increased. Air piracy, terrorism and other criminal acts remain a real threat to all air crew members. The commitment and cooperation of all national authorities as well as the force of worldwide public opinion are needed to prevent these acts. Additionally, air crew members must continue to receive special training and information on security measures and must be informed on a timely basis of suspected threats of air piracy and terrorism.

Air crew members understand the importance of starting flight duty in a sufficiently good mental and physical state to ensure that the fatigue and stresses occasioned by the flight itself will not affect safety. Fitness for flight duty may occasionally be impaired by psychological and physical stress, and it is the responsibility of the crew member to recognize whether or not he or she is fit for duty. Sometimes, however, these effects may not be readily apparent to the person under duress. For this reason, most airlines and air crew member associations and labour unions have professional standards committees to assist crew members in this area.

Accidents

Fortunately, catastrophic aircraft accidents are rare events; nonetheless, they do represent a hazard for air crew members. An aircraft accident is practically never a hazard resulting from a single, well-defined cause; in almost every instance, a number of technical and human factors coincide in the causal process.

Defective equipment design or equipment failure, especially as a result of inadequate maintenance, are two mechanical causes of aircraft accidents. One important, although relatively rare, type of human failure is sudden death due, for example, to myocardial infarction; other failures include sudden loss of consciousness (e.g., epileptic fit, cardiac syncope and fainting due to food poisoning or other intoxication). Human failure may also result from the slow deterioration of certain functions such as hearing or vision, although no major aircraft accident has been attributed to such a cause. Preventing accidents from medical causes is one of the most important tasks of aviation medicine. Careful personnel selection, regular medical examinations, surveys of absence due to illness and accidents, continuous medical contact with working conditions and industrial hygiene surveys can considerably decrease the danger of sudden incapacitation or slow deterioration in technical crew. Medical personnel should also routinely monitor flight scheduling practices to prevent fatigue-related incidents and accidents. A well-operated, modern airline of significant size should have its own medical service for these purposes.

Advances in aircraft accident prevention are often made as a result of careful investigation of accidents and incidents. Systematic screening of all, even minor, accidents and incidents by an accident investigation board comprising technical, operational, structural, medical and other experts is essential to determine all causal factors in an accident or incident and to make recommendations for preventing future occurrences.

A number of strict regulations exist in aviation to prevent accidents caused by use of alcohol or other drugs. Crew members should not consume quantities of alcohol in excess of what is compatible with professional requirements, and no alcohol at all should be consumed during and for at least 8 hours prior to flight duty. Illegal drug use is strictly prohibited. Drug use for medicinal purposes is strictly controlled; such drugs are generally not allowed during or immediately preceding flight, although exceptions may be allowed by a recognized flight physician.

The transport of hazardous materials by air is yet another cause of aircraft accident and incidents. A recent survey covering a 2-year period (1992 to 1993) identified over 1,000 aircraft incidents involving hazardous materials on passenger and cargo air carriers in one nation alone. More recently, an accident in the United States which resulted in the deaths of 110 passengers and crew involved the carriage of hazardous cargo. Hazardous materials incidents in air transportation occur for a number of reasons. Shippers and passengers may be unaware of the dangers presented by the materials they bring aboard aircraft in their baggage or offer for transport. Occasionally, unscrupulous persons may choose to illegally ship forbidden hazardous materials. Additional restrictions on the carriage of hazardous materials by air and improved training for air crew members, passengers, shippers and loaders may help to prevent future incidents. Other accident prevention regulations deal with oxygen supply, crew meals and procedures in case of illness.

Diseases

Specific occupational disease of crew members are not known or documented. However, certain diseases may be more prevalent among crew members than among persons in other occupations. Common colds and upper respiratory system infections are frequent; this may be due in part to the low humidity during flight, irregularities of schedules, exposure to att large number of people in a confined space and so on. A common cold, especially with upper respiratory congestion, that is not significant for an office worker may incapacitate a crew member if it prevents the clearing of pressure on the middle ear during ascent and, particularly, during descent. Additionally, illnesses that require some form of drug therapy may also preclude the crew member from engaging in work for a period of time. Frequent travel to tropical areas may also entail increased exposure to infectious diseases, the most important being malaria and infections of the digestive system.

The close confines of an aircraft for extended periods of time also carry an excess risk of airborne infectious diseases like tuberculosis, if a passenger or crew member has such a disease in its contagious stage.

 

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Monday, 21 March 2011 15:24

Art Teaching

Health and safety problems in art programmes can be similar in educational institutions ranging from junior high schools to universities. Arts programmes are a special problem because their hazards are not often recognized and, especially at the college level, can be semi-industrial in scale. Hazards can include inhalation of airborne contaminants; ingestion or dermal absorption of toxins; injury from machinery and tools; slips, trips and falls; and repetitive strain and other musculoskeletal injuries. Precautions include the provision of adequate ventilation (both dilution and local exhaust), the safe handling and storage of chemicals, machine-guarding and competent maintenance of machinery, efficient clean-up, good housekeeping and adjustable work stations. A key precaution in avoiding occupational safety and health problems of all kinds is adequate and mandatory training.

Elementary and Secondary School Teachers

Hazards at the elementary and secondary school levels include practices such as spraying and unsafe use of solvents and other chemicals and poor ventilation of processes. There is frequently a lack of proper equipment and sufficient knowledge of materials to ensure a safe workplace. Precautions include efficient engineering controls, better knowledge of materials, the elimination of hazardous art supplies from schools and substitution with safer ones (see table 1). This will help protect not only teachers, technicians, maintenance workers and administrators, but also students.

Table 1. Hazards and precautions for particular classes.

Class

Activity/Subject

Hazards

Precautions

Elementary Classes

Science

Animal handling

 

 

Plants

 

Chemicals

 

 

Equipment

 

Bites and scratches,

zoonoses, parasites

 

Allergies, poisonous plants

 

Skin and eye problems,

toxic reactions, allergies

 

Electrical hazards,

safety hazards

Allow only live, healthy animals. Handle animals with heavy gloves. Avoid

animals which can carry disease-transmitting insects and parasites.

 

Avoid plants which are known to be poisonous or cause allergic reaction.

 

Avoid using toxic chemicals with children. Wear proper personal protective

equipment when doing teacher demonstrations with toxic chemicals.

 

Follow standard electrical safety procedures. Ensure all equipment is properly

guarded. Store all equipment, tools, etc., properly.

 

Art

 

 

 

Painting and drawing

 

Photography

 

 

Textile and fibre arts

 

Printmaking

 

 

 

Woodworking

 

 

 

Ceramics

 

 

 

Pigments, solvents

 

Photochemicals

 

 

Dyes

 

Acids, solvents

 

Cutting tools

 

Tools

 

Glues

 

Silica, toxic metals, heat,

kiln fumes

Use only non-toxic art materials. Avoid solvents, acids, alkalis, spray cans, chemical dyes, etc.

 

Use only children’s paints. Do not use pastels, dry pigments.

 

Do not do photoprocessing. Send out film for developing or use Polaroid cameras

or blueprint paper and sunlight.

 

Avoid synthetic dyes; use natural dyes such as onion skins, tea, spinach, etc.

 

Use water-based block printing inks.

 

Use linoleum cuts instead of woodcuts.

 

Use soft woods and hand tools only.

 

Use water-based glues.

 

Use wet clay only, and wet mop.

Paint pottery rather than using ceramic glazes. Do not fire kiln inside classroom.

 

 

Secondary Classes

 

Chemistry

General

 

 

 

 

 

 

Organic chemistry

 

 

 

 

 

 

Inorganic chemistry

 

Analytical chemistry

 

Storage

 

 

 

 

 

 

 

Solvents

 

 

 

Peroxides and explosives

 

 

Acids and bases

 

Hydrogen sulphide

 

Incompatibilities

 

 

Flammability

All school laboratories should have the following: laboratory hood if toxic, volatile

chemicals are used; eyewash fountains; emergency showers (if concentrated

acids, bases or other corrosive chemicals are present); first aid kits; proper fire

extinguishers; protective goggles, gloves and lab coats; proper disposal

receptacles and procedures; spill control kit. Avoid carcinogens, mutagens and

highly toxic chemicals like mercury, lead, cadmium, chlorine gas, etc.

 

Use only in laboratory hood.

Use least toxic solvents.

Do semi-micro- or microscale experiments.

 

Do not use explosives or chemicals such as ether, which can form explosive

peroxides.

 

Avoid concentrated acids and bases when possible.

 

Do not use hydrogen sulphide. Use substitutes.

 

Avoid alphabetical storage, which can place incompatible chemicals in close

proximity. Store chemicals by compatible groups.

 

Store flammable and combustible liquids in approved flammable-storage

cabinets.

 

Biology

Dissection

 

 

Anaesthetizing insects

 

Drawing of blood

 

Microscopy

 

Culturing bacteria

Formaldehyde

 

 

Ether, cyanide

 

HIV, Hepatitis B

 

Stains

 

Pathogens

Do not dissect specimens preserved in formaldehyde. Use smaller, freeze-dried

animals, training films and videotapes, etc.

 

Use ethyl alcohol for anaesthetization of insects. Refrigerate insects for counting.

 

Avoid if possible. Use sterile lancets for blood typing under close supervision.

 

Avoid skin contact with iodine and gentian violet.

 

Use sterile technique with all bacteria, assuming there could be contamination by

pathogenic bacteria.

 

Physical sciences

Radioisotopes

 

 

Electricity and magnetism

 

Lasers

Ionizing radiation

 

 

Electrical hazards

 

 

Eye and skin damage,

electrical hazards

Use radioisotopes only in “exempt” quantities not requiring a license. Only trained

teachers should use these. Develop a radiation safety programme.

 

Follow standard electrical safety procedures.

 

 

Use only low-power (Class I) lasers. Never look directly into a laser beam or pass

the beam across face or body. Lasers should have a key lock.

 

Earth sciences

Geology

 

Water pollution

 

 

Atmosphere

 

 

Volcanoes

 

Solar observation

Flying chips

 

Infection, toxic chemicals

 

 

Mercury manometers

 

 

Ammonium dichromate

 

Infrared radiation

Crush rocks in canvas bag to prevent flying chips. Wear protective goggles.

 

Do not take sewage samples because of infection risk. Avoid hazardous

chemicals in field testing of water pollution.

 

Use oil or water manometers. If mercury manometers are used for demonstration,

have mercury spill control kit.

 

Do not use ammonium dichromate and magnesium to simulate volcanoes.

 

Never view sun directly with eyes or through lenses.

 

Art and Industrial Arts

All

 

 

Painting and drawing

 

 

Photography

 

 

Textile and fibre arts

General

 

 

Pigments, solvents

 

 

Photochemicals, acids,

sulphur dioxide

 

Dyes, dyeing assistants,

wax fumes

Avoid most dangerous chemicals and processes. Have proper ventilation. See

also precautions under Chemistry

 

Avoid lead and cadmium pigments. Avoid oil paints unless cleanup is done with

vegetable oil. Use spray fixatives outside.

 

Avoid colour processing and toning. Have dilution ventilation for darkroom. Have

eyewash fountain. Use water instead of acetic acid for stop bath.

 

Use aqueous liquid dyes or mix dyes in glove box. Avoid dichromate mordants.

Do not use solvents to remove wax in batik. Have ventilation if ironing out wax.

 

 

Papermaking

 

 

 

Printmaking

 

 

 

 

 

 

 

 

 

 

Woodworking

 

 

 

 

 

 

 

 

 

 

 

 

 

Ceramics

 

 

 

Sculpture

 

 

 

 

Jewelry

 

Alkali, beaters

 

 

 

Solvents

 

 

 

Acids, potassium chlorate

 

 

 

Dichromates

 

 

Woods and wood dust

 

 

 

Machinery and tools

 

Noise

 

Glues

 

 

Paints and finishes

 

 

Lead, silica, toxic metals, kiln fumes

 

 

Silica, plastics resins, dust

 

 

 

 

Soldering fumes, acids

Do not boil lye. Use rotten or mulched plant materials, or recycle paper and

cardboard. Use large blender instead of more dangerous industrial beaters to

prepare paper pulp.

 

Use water-based instead of solvent-based silk screen inks. Clean intaglio press

beds nd inking slabs with vegetable oil and dishwashing liquid instead of solvents.

Use cut paper stencils instead of lacquer stencils for silk screen printing.

 

Use ferric chloride to etch copper plates instead of Dutch mordant or nitric acid on

zinc plates. If using nitric acid etching, have emergency shower and eyewash

fountain and local exhaust ventilation.

 

Use diazo instead of dichromate photoemulsions. Use citric acid fountain

solutions in lithography to replace dichromates.

 

Have dust collection system for woodworking machines. Avoid irritating and

allergenic hardwoods, preserved woods (e.g., chromated copper arsenate

treated).Clean up wood dust to remove fire hazards.

 

Have machine guards. Have key locks and panic button.

 

Reduce noise levels or wear hearing protectors.

 

Use water-based glues when possible. Avoid formaldehyde/resorcinol glues,

solvent-based glues.

 

Use water-based paints and finishes. Use shellac based on ethyl alcohol rather

than methyl alcohol.

 

Purchase wet clay. Do not use lead glazes. Buy prepared glazes rather than

mixing dry glazes. Spray glazes only in spray booth. Fire kiln outside or have

local exhaust ventilation. Wear infrared goggles when looking into hot kiln.

 

Use only hand tools for stone sculpture to reduce dust levels. Do not use

sandstone, granite or soapstone, which might contain silica or asbestos. Do not

use highly toxic polyester, epoxy or polyurethane resins. Have ventilation if

heating plastics to remove decomposition products. Wet mop or vacuum dusts.

 

Avoid cadmium silver solders and fluoride fluxes. Use sodium hydrogen sulphate rather than sulphuric acid for pickling. Have local exhaust ventilation.

 

 

Enameling

 

 

Lost wax casting

 

 

 

Stained glass

 

 

Welding

 

 

 

Commercial art

Lead, burns, infrared

radiation

 

Metal fumes, silica,

infrared radiation, heat

 

 

Lead, acid fluxes

 

 

Metal fumes, ozone, nitrogen

dioxide, electrical and fire

hazards

 

Solvents, photochemicals,

video display terminals

Use only lead-free enamels. Ventilate enameling kiln. Have heat-protective

gloves and clothing, and infrared goggles.

 

Use 50/50 30-mesh sand/plaster instead of cristobalite investments. Have local

exhaust ventilation for wax burnout kiln and casting operation. Wear heat-pro

tective clothing and gloves.

 

Use copper foil technique rather than lead came. Use lead- and antimony-free

solders. Avoid lead glass paints. Use acid- and rosin-free soldering fluxes.

 

Do not weld metals coated with zinc, lead paints, or alloys with hazardous metals

(nickel, chromium, etc.). Weld only metals of known composition.

 

 

Use double-sided tape instead of rubber cement. Use heptane-based, not hexane

rubber cements. Have spray booths for air brushing. Use water-based or alcohol-

based permanent markers instead of xylene types.

See Photography section for photoprocesses.

Have proper ergonomic chairs, lighting, etc., for computers.

 

Performing Arts

Theatre

 

 

 

 

Dance

 

 

 

Music

Solvents, paints, welding

fumes, isocyanates, safety,

fire

 

 

Acute injuries

Repetitive strain injuries

 

 

Musculoskeletal injuries

(e.g., carpal tunnel syndrome)

 

Noise

 

 

 

Vocal strain

Use water-based paints and dyes. Do not use polyurethane spray foams.

Separate welding from other areas. Have safe rigging procedures. Avoid

pyrotechnics, firearms, fog and smoke, and other hazardous special effects.

Fireproof all stage scenery. Mark all trap doors, pits and elevations.

 

Have a proper dance floor. Avoid full schedules after period of inactivity. Assure

proper warm-up before and cool-down after dance activity. Allow sufficient

recovery time after injuries.

 

Use proper sized instruments. Have adequate instrument supports. Allow sufficient recovery time after injuries.

 

Keep sound levels at acceptable levels. Wear musician’s ear plugs if needed.

Position speakers to minimize noise levels. Use sound-absorbing materials on

walls.

 

Assure adequate warm-up. Provide proper vocal training and conditioning.

 

Automotive Mechanics

Brake drums

 

Degreasing

 

Car motors

 

Welding

 

Painting

Asbestos

 

Solvents

 

Carbon monoxide

 

 

 

Solvents, pigments

Do not clean brake drums unless approved equipment is used.

 

Use water-based detergents. Use parts cleaner

 

Have tailpipe exhaust.

 

See above.

 

Spray paint only in spray booth, or outdoors with respiratory protection.

 

 

Home Economics

Food and nutrition

Electrical hazards

 

Knives and other sharp

utensils

 

Fire and burns

 

 

Cleaning products

Follow standard electrical safety rules.

 

Always cut away from body. Keep knives sharpened.

 

 

Have stove hoods with grease filters that exhaust to outside. Wear protective

gloves with hot objects.

 

Wear goggles, gloves and apron with acidic or basic cleaning products.

 

 

College and University Teachers

Hazards at the college and university levels include, in addition to those mentioned above, the fact that students, teachers and technicians tend to be more experimental and tend to use more potentially dangerous materials and machinery. They also often work on a larger scale and for longer periods of time. Precautions must include education and training, the provision of engineering controls and personal protective equipment, written safety policies and procedures and insistence on compliance with these.

Artistic Freedom

Many art teachers and technicians are artists in their own right, resulting in multiple exposures to the hazards of art materials and processes which can significantly increase their health risks. When confronted with hazards in their field about which they have not known or which they have ignored, many teachers become defensive. Artists are experimental and frequently belong to an anti-establishment culture which encourages defiance of institutional rules. It is important, however, for the school administration to realize that the quest for artistic freedom is not a valid argument against working safely.

Liability and Training

In many jurisdictions teachers will be subject to both a personal and a school liability for the safety of their students, particularly the younger ones. “Because of the age, maturity, and experience limitations of most students, and because teachers stand in loco parentis (in the place of a parent), schools are expected to provide a safe environment and establish reasonable behaviour for the protection of students” (Qualley 1986).

Health and Safety Programmes

It is important that schools take the responsibility for training both art teachers and school administrators in the potential hazards of art materials and processes and in how to protect their students and themselves. A prudent school administration will ensure that there are in place written health and safety policies, procedures and programmes, compliance with these, regular safety training and a real interest in teaching how to create art safely.

 

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Thursday, 24 March 2011 15:03

Metalworking

Metalworking involves casting, welding, brazing, forging, soldering, fabrication and surface treatment of metal. Metalworking is becoming even more common as artists in developing countries are also starting to use metal as a basic sculptural material. While many art foundries are commercially run, art foundries are also often part of college art programmes.

Hazards and Precautions

Casting and foundry

Artists either send work out to commercial foundries, or can cast metal in their own studios. The lost wax process is often used for casting small pieces. Common metals and alloys used are bronze, aluminium, brass, pewter, iron and stainless steel. Gold, silver and sometimes platinum are used for casting small pieces, particularly for jewellery.

The lost wax process involves several steps:

  1. making the positive form
  2. making the investment mould
  3. burning out of the wax
  4. melting the metal
  5. slagging
  6. pouring the molten metal into the mould
  7. removing the mould

 

The positive form can be made directly in wax; it can also be made in plaster or other materials, a negative mould made in rubber and then the final positive form cast in wax. Heating the wax can result in fire hazards and in decomposition of the wax from overheating.

The mould is commonly made by applying an investment containing the cristobalite form of silica, creating the risk of silicosis. A 50/50 mixture of plaster and 30-mesh sand is a safer substitute. Moulds can also be made using sand and oil, formaldehyde resins and other resins as binders. Many of these resins are toxic by skin contact and inhalation, requiring skin protection and ventilation.

The wax form is burnt out in a kiln. This requires local exhaust ventilation to remove the acrolein and other irritating wax decomposition products.

Melting the metal is usually done in a gas-fired crucible furnace. A canopy hood exhausted to the outside is needed to remove carbon monoxide and metal fumes, including zinc, copper, lead, aluminium and so on.

The crucible containing the molten metal is then removed from the furnace, the slag on the surface removed and the molten metal poured into the moulds (figure 1). For weights under 80 pounds of metal, manual lifting is normal; for greater weights, lifting equipment is needed. Ventilation is needed for the slagging and pouring operations to remove metal fumes. Resin sand moulds can also produce hazardous decomposition products from the heat. Face shields protecting against infrared radiation and heat, and personal protective clothing resistant to heat and molten metal splashes are essential. Cement floors must be protected against molten metal splashes by a layer of sand.

Figure 1. Pouring molten metal in art foundry.

ENT060F1

Ted Rickard

Breaking away the mould can result in exposure to silica. Local exhaust ventilation or respiratory protection is needed. A variation of the lost wax process called the foam vaporization process involves using polystyrene or polyurethane foam instead of wax, and vaporizing the foam during pouring of the molten metal. This can release hazardous decomposition products, including hydrogen cyanide from polyurethane foam. Artists often use scrap metal from a variety of sources. This practice can be dangerous due to possible presence of lead- and mercury-containing paints, and to the possible presence of metals like cadmium, chromium, nickel and so on in the metals.

Fabrication

Metal can be cut, drilled and filed using saws, drills, snips and metal files. The metal filings can irritate the skin and eyes. Electric tools can cause electric shock. Improper handling of these tools can result in accidents. Goggles are needed to protect the eyes from flying chips and filings. All electrical equipment should be properly grounded. All tools should be carefully handled and stored. Metal to be fabricated should be securely clamped to prevent accidents.

Forging

Cold forging utilizes hammers, mallets, anvils and similar tools to change the shape of metal. Hot forging involves additionally heating the metal. Forging can create great amounts of noise, which can cause hearing loss. Small metal splinters may damage the skin or eyes if precautions are not taken. Burns are also a hazard with hot forging. Precautions include good tools, eye protection, routine clean-up, proper work clothing, isolation of the forging area and wearing ear plugs or ear muffs.

Hot forging involves the burning of gas, coke or other fuels. A canopy hood for ventilation is needed to exhaust carbon monoxide and possible polycyclic aromatic hydrocarbon emissions, and to reduce heat build-up. Infrared goggles should be worn for protection against infrared radiation.

Surface treatment

Mechanical treatment (chasing, repousse) is done with hammers, engraving with sharp tools, etching with acids, photoetching with acids and photochemicals, electroplating (plating a metallic film onto another metal) and electroforming (plating a metallic film onto a non-metallic object) with acids and cyanide solutions and metal colouring with many chemicals.

Electroplating and electroforming often use cyanide salts, ingestion of which can be fatal. Accidental mixing of acids and the cyanide solution will produce hydrogen cyanide gas. This is hazardous through both skin absorption and inhalation—death can occur within minutes. Disposal and waste management of spent cyanide solutions is strictly regulated in many countries. Electroplating with cyanide solutions should be done in a commercial plant; otherwise use substitutes that do not contain cyanide salts or other cyanide-containing materials.

Acids are corrosive, and skin and eye protection is needed. Local exhaust ventilation with acid-resistant ductwork is recommended.

Anodizing metals such as titanium and tantalum involves oxidizing these at the anode of an electrolytic bath to colour them. Hydrofluoric acid can be used for precleaning. Avoid using hydrofluoric acid or use gloves, goggles and a protective apron.

Patinas used to colour metals can be applied cold or hot. Lead and arsenic compounds are very toxic in any form, and others can give off toxic gases when heated. Potassium ferricyanide solutions will give off hydrogen cyanide gas when heated, arsenic acid solutions give off arsine gas and sulphide solutions give off hydrogen sulphide gas. Very good ventilation is needed for metal colouring (figure 2). Arsenic compounds and heating of potassium ferrocyanide solutions should be avoided.

Figure 2. Applying a patina to metal with slot exhaust hood.

ENT060F2

Ken Jones

Finishing processes

Cleaning, grinding, filing, sandblasting and polishing are some final treatments for metal. Cleaning involves the use of acids (pickling). This involves the hazards of handling acids and of the gases produced during the pickling process (such as nitrogen dioxide from nitric acid). Grinding can result in the production of fine metal dusts (which can be inhaled) and heavy flying particles (which are eye hazards).

Sandblasting (abrasive blasting) is very hazardous, particularly with actual sand. Inhalation of fine silica dust from sandblasting can cause silicosis in a short time. Sand should be replaced with glass beads, aluminium oxide or silicon carbide. Foundry slags should be used only if chemical analysis shows no silica or dangerous metals such as arsenic or nickel. Good ventilation or respiratory protection is needed.

Polishing with abrasives such as rouge (iron oxide) or tripoli can be hazardous since rouge can be contaminated with large amounts of free silica, and tripoli contains silica. Good ventilation of the polishing wheel is needed.

Welding

Physical hazards in welding include the danger of fire, electric shock from arc-welding equipment, burns caused by molten metal sparks, and injuries caused by excessive exposure to infrared and ultraviolet radiation. Welding sparks can travel 40 feet.

Infrared radiation can cause burns and eye damage. Ultraviolet radiation can cause sunburn; repeated exposure may lead to skin cancer. Electric arc welders in particular are subject to pink eye (conjunctivitis), and some have cornea damage from UV exposure. Skin protection and welding goggles with UV- and IR-protective lenses are needed.

Oxyacetylene torches produce carbon monoxide, nitrogen oxides and unburned acetylene, which is a mild intoxicant. Commercial acetylene contains small amounts of other toxic gases and impurities.

Compressed gas cylinders can be both explosive and fire hazards. All cylinders, connections and hoses must be carefully maintained and inspected. All gas cylinders must be stored in a location which is dry, well ventilated and secure from unauthorized persons. Fuel cylinders must be stored separately from oxygen cylinders.

Arc welding produces enough energy to convert the air’s nitrogen and oxygen to nitrogen oxides and ozone, which are lung irritants. When arc welding is done within 20 feet of chlorinated degreasing solvents, phosgene gas can be produced by the UV radiation.

Metal fumes are generated by the vaporization of metals, metal alloys and the electrodes used in arc welding. Fluoride fluxes produce fluoride fumes.

Ventilation is needed for all welding processes. While dilution ventilation may be adequate for mild steel welding, local exhaust ventilation is necessary for most welding operations. Moveable flanged hoods, or lateral slot hoods should be used. Respiratory protection is needed if ventilation is not available.

Many metal dusts and fumes can cause skin irritation and sensitization. These include brass dust (copper, zinc, lead and tin), cadmium, nickel, titanium and chromium.

In addition, there are problems with welding materials that may be coated with various substances (e.g., lead or mercury paint).

 

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Since the first sustained flight of a powered aircraft at Kitty Hawk, North Carolina (United States), in 1903, aviation has become a major international activity. It is estimated that from 1960 to 1989, the annual number of air passengers of regularly scheduled flights increased from 20 million to over 900 million (Poitrast and deTreville 1994). Military aircraft have become indispensable weapons systems for the armed forces of many nations. Advances in aviation technology, in particular the design of life support systems, have contributed to the rapid development of space programmes with human crews. Orbital space flights occur relatively frequently, and astronauts and cosmonauts work in space vehicles and space stations for extended periods of time.

In the aerospace environment, physical stressors that may affect the health of aircrew, passengers and astronauts to some degree include reduced concentrations of oxygen in the air, decreased barometric pressure, thermal stress, acceleration, weightlessness and a variety of other potential hazards (DeHart 1992). This article describes aeromedical implications of exposure to gravity and acceleration during flight in the atmosphere and the effects of microgravity experienced in space.

Gravity and Acceleration

The combination of gravity and acceleration encountered during flight in the atmosphere produces a variety of physiological effects experienced by aircrew and passengers. At the surface of the earth, the forces of gravity affect virtually all forms of human physical activity. The weight of a person corresponds to the force exerted upon the mass of the human body by the earth’s gravitational field. The symbol used to express the magnitude of the acceleration of an object in free fall when it is dropped near the earth’s surface is referred to as g, which corresponds to an acceleration of approximately 9.8 m/s2 (Glaister 1988a; Leverett and Whinnery 1985).

Acceleration occurs whenever an object in motion increases its velocity. Velocity describes the rate of movement (speed) and direction of motion of an object. Deceleration refers to acceleration that involves a reduction in established velocity. Acceleration (as well as deceleration) is a vector quantity (it has magnitude and direction). There are three types of acceleration: linear acceleration, a change of speed without change in direction; radial acceleration, a change in direction without a change of speed; and angular acceleration, a change in speed and direction. During flight, aircraft are capable of manoeuvring in all three directions, and crew and passengers may experience linear, radial and angular accelerations. In aviation, applied accelerations are commonly expressed as multiples of the acceleration due to gravity. By convention, G is the unit expressing the ratio of an applied acceleration to the gravitational constant (Glaister 1988a; Leverett and Whinnery 1985).

Biodynamics

Biodynamics is the science dealing with the force or energy of living matter and is a major area of interest within the field of aerospace medicine. Modern aircraft are highly manoeuvrable and capable of flying at very high speeds, causing accelerative forces upon the occupants. The influence of acceleration upon the human body depends upon the intensity, rate of onset and direction of acceleration. The direction of acceleration is generally described by the use of a three-axis coordinate system (x, y, z) in which the vertical (z) axis is parallel to the long axis of the body, the x axis is oriented from front to back, and the y axis oriented side to side (Glaister 1988a). These accelerations can be categorized into two general types: sustained and transitory.

Sustained acceleration

The occupants of aircraft (and spacecraft operating in the atmosphere under the influence of gravity during launch and re-entry) commonly experience accelerations in response to aerodynamic forces of flight. Prolonged changes in velocity involving accelerations lasting longer than 2 seconds may result from changes in an aircraft’s speed or direction of flight. The physiological effects of sustained acceleration result from the sustained distortion of tissues and organs of the body and changes in the flow of blood and distribution of body fluids (Glaister 1988a).

Positive or headward acceleration along the z axis (+Gz) represents the major physiological concern. In civil air transportation, Gz accelerations are infrequent, but may occasionally occur to a mild degree during some take-offs and landings, and while flying in conditions of air turbulence. Passengers may experience brief sensations of weightlessness when subject to sudden drops (negative Gz accelerations), if unrestrained in their seats. An unexpected abrupt acceleration may cause unrestrained aircrew or passengers to be thrown against internal surfaces of the aircraft cabin, resulting in injuries.

In contrast to civil transport aviation, the operation of high- performance military aircraft and stunt and aerial spray planes may generate significantly higher linear, radial and angular accelerations. Substantial positive accelerations may be generated as a high-performance aircraft changes its flight path during a turn or a pull-up manoeuvre from a steep dive. The +Gz performance characteristics of current combat aircraft may expose occupants to positive accelerations of 5 to 7 G for 10 to 40 seconds (Glaister 1988a). Aircrew may experience an increase in the weight of tissues and of the extremities at relatively low levels of acceleration of only +2 Gz. As an example, a pilot weighing 70 kg who performed an aircraft manoeuvre which generated +2 Gz would experience an increase of body weight from 70 kg to 140 kg.

The cardiovascular system is the most important organ system for determining the overall tolerance and response to +Gz stress (Glaister 1988a). The effects of positive acceleration on vision and mental performance are due to decreases in blood flow and delivery of oxygen to eye and brain. The capability of the heart to pump blood to the eyes and brain is dependent upon its capability to exceed the hydrostatic pressure of blood at any point along the circulatory system and the inertial forces generated by the positive Gz acceleration. The situation may be likened to that of pulling upward a balloon partially full of water and observing the downward distension of the balloon because of the resultant inertial force acting upon the mass of water. Exposure to positive accelerations may cause temporary loss of peripheral vision or complete loss of consciousness. Military pilots of high- performance aircraft may risk development of G-induced blackouts when exposed to rapid onset or extended periods of positive acceleration in the +Gz axis. Benign cardiac arrhythmias frequently occur following exposure to high sustained levels of +Gz acceleration, but usually are of minimal clinical significance unless pre-existing disease is present; –Gz acceleration seldom occurs because of limitations in aircraft design and performance, but may occur during inverted flight, outside loops and spins and other similar manoeuvres. The physiological effects associated with exposure to –Gz acceleration primarily involve increased vascular pressures in the upper body, head and neck (Glaister 1988a).

Accelerations of sustained duration which act at right angles to the long axis of the body are termed transverse accelerations and are relatively uncommon in most aviation situations, with the exception of catapult and jet- or rocket-assisted take-offs from aircraft carriers, and during launch of rocket systems such as the space shuttle. The accelerations encountered in such military operations are relatively small, and usually do not affect the body in a major fashion because the inertial forces act at right angles to the long axis of the body. In general, the effects are less pronounced than in Gz accelerations. Lateral acceleration in ±Gy axis are uncommon, except with experimental aircraft.

Transitory acceleration

The physiological responses of individuals to transitory accelerations of short duration are a major consideration in the science of aircraft accident prevention and crew and passenger protection. Transitory accelerations are of such brief duration (considerably less than 1 second) that the body is unable to attain a steady-state status. The most common cause of injury in aircraft accidents results from the abrupt deceleration that occurs when an aircraft impacts the ground or water (Anton 1988).

When an aircraft impacts the ground, a tremendous amount of kinetic energy applies damaging forces to the aircraft and its occupants. The human body responds to these applied forces by a combination of acceleration and strain. Injuries result from deformation of tissues and organs and trauma to anatomic parts caused by collision with structural components of the aircraft cockpit and/or cabin.

Human tolerance to abrupt deceleration is variable. The nature of injuries will depend on the nature of the applied force (whether it primarily involves penetrating or blunt impact). At impact, the forces which are generated are dependent on the longitudinal and horizontal decelerations which are generally applied to an occupant. Abrupt decelerative forces are often categorized into tolerable, injurious and fatal. Tolerable forces produce traumatic injuries such as abrasions and bruises; injurious forces produce moderate to severe trauma which may not be incapacitating. It is estimated that an acceleration pulse of approximately 25 G maintained for 0.1 second is the limit of tolerability along the +Gz axis, and that about 15 G for 0.1 sec is the limit for the –Gz axis (Anton 1988).

Multiple factors affect human tolerance to short-duration acceleration. These factors include the magnitude and duration of the applied force, the rate of onset of the applied force, its direction and the site of application. It should be noted that people can withstand much greater forces perpendicular to the long axis of the body.

Protective Countermeasures

Physical screening of crew members to identify serious pre- existing diseases which might put them at increased risk in the aerospace environment is a key function of aeromedical programmes. In addition, countermeasures are available to crew of high-performance aircraft to protect against the adverse effects of extreme accelerations during flight. Crew members must be trained to recognize that multiple physiological factors may decrease their tolerance to G stress. These risk factors include fatigue, dehydration, heat stress, hypoglycemia and hypoxia (Glaister 1988b).

Three types of manoeuvres which crew members of high- performance aircraft employ to minimize adverse effects of sustained acceleration during flight are muscle tensing, forced expiration against a closed or partially closed glottis (back of the tongue) and positive-pressure breathing (Glaister 1988b; DeHart 1992). Forced muscle contractions exert increased pressure on blood vessels to decrease venous pooling and increase venous return and cardiac output, resulting in increased blood flow to the heart and upper body. While effective, the procedure requires extreme, active effort and may rapidly result in fatigue. Expiration against a closed glottis, termed the Valsalva manoeuver (or M-1 procedure) can increase pressure in the upper body and raise the intrathoracic pressure (inside the chest); however, the result is short lived and may be detrimental if prolonged, because it reduces venous blood return and cardiac output. Forcibly exhaling against a partially closed glottis is a more effective anti-G straining manoeuver. Breathing under positive pressure represents another method to increase intrathoracic pressure. Positive pressures are transmitted to the small artery system, resulting in increased blood flow to the eyes and brain. Positive-pressure breathing must be combined with the use of anti-G suits to prevent excessive pooling in the lower body and limbs.

Military aircrew practise a variety of training methods to enhance G tolerance. Crews frequently train in a centrifuge consisting of a gondola attached to a rotating arm which spins and generates +Gz acceleration. Aircrew become familiar with the spectrum of physiological symptoms which may develop and learn the proper procedures to control them. Physical fitness training, particularly whole-body strength training, also has been found to be effective. One of the most common mechanical devices used as protective equipment to reduce the effects of +G exposure consists of pneumatically inflated anti-G suits (Glaister 1988b). The typical trouser-like garment consists of bladders over the abdomen, thighs and calves which automatically inflate by means of an anti-G valve in the aircraft. The anti-G valve inflates in reaction to an applied acceleration upon the aircraft. Upon inflation, the anti-G suit produces a rise in the tissue pressures of the lower extremities. This maintains peripheral vascular resistance, reduces the pooling of blood in the abdomen and lower limbs and minimizes downward displacement of the diaphragm to prevent the increase in the vertical distance between the heart and brain that may be caused by positive acceleration (Glaister 1988b).

Surviving transitory accelerations associated with aircraft crashes is dependent on effective restraint systems and the maintenance of the cockpit/cabin integrity to minimize intrusion of damaged aircraft components into the living space (Anton 1988). The function of lap belts, harnesses and other types of restraint systems are to limit the movement of the aircrew or passengers and to attenuate the effects of sudden deceleration during impact. The effectiveness of the restraint system depends on how well it transmits loads between the body and the seat or vehicle structure. Energy-attenuating seating and rearward facing seats are other features in aircraft design which limit injury. Other accident-protection technology includes the design of airframe components to absorb energy and improvements in seat structures to reduce mechanical failure (DeHart 1992; DeHart and Beers 1985).

Microgravity

Since the 1960s, astronauts and cosmonauts have flown numerous missions into space, including 6 lunar landings by Americans. Mission duration has been from several days to a number of months, with a few Russian cosmonauts logging approximately 1-year flights. Subsequent to these space flights, a large body of literature has been written by physicians and scientists describing in-flight and post-flight physiological aberrations. For the most part, these aberrations have been attributed to exposure to weightlessness or microgravity. Although these changes are transient, with total recovery within several days to several months after returning to Earth, nobody can say with complete certitude whether astronauts would be so fortunate after missions lasting 2 to 3 years, as envisioned for a round trip to Mars. The major physiological aberrations (and countermeasures) can be categorized as cardiovascular, musculoskeletal, neurovestibular, haematological and endocrinological (Nicogossian, Huntoon and Pool 1994).

Cardiovascular hazards

Thus far, there have been no serious cardiac problems in space, such as heart attacks or heart failure, although several astronauts have developed abnormal heart rhythms of a transient nature, particularly during extra-vehicular activity (EVA). In one case, a Russian cosmonaut had to return to Earth earlier than planned, as a precautionary measure.

On the other hand, microgravity seems to induce a lability of blood pressure and pulse. Although this does not cause impaired health or crew performance during flight, approximately half of astronauts immediately post-flight do become extremely dizzy and giddy, with some experiencing fainting (syncope) or near fainting (pre-syncope). The cause of this intolerance to being vertical is thought to be a drop in blood pressure upon re-entering the earth’s gravitational field, combined with the dysfunction of the body’s compensatory mechanisms. Hence, a low blood pressure and decreasing pulse unopposed by the body’s normal response to such physiological aberrations results in these symptoms.

Although these pre-syncopal and syncopal episodes are transient and without sequelae, there remains great concern for several reasons. First, in the event that a returning space vehicle were to have an emergency, such as a fire, upon landing, it would be extremely difficult for astronauts to rapidly escape. Second, astronauts landing on the moon after periods of time in space would be prone to some extent to pre-fainting and fainting, even though the moon’s gravitational field is one-sixth that of Earth. And finally, these cardiovascular symptoms might be far worse or even lethal after very long missions.

It is for these reasons that there has been an aggressive search for countermeasures to prevent or at least ameliorate the microgravity effects upon the cardiovascular system. Although there are a number of countermeasures now being studied that show some promise, none so far has been proven truly effective. Research has focused on in-flight exercise utilizing a treadmill, bicycle ergometer and rowing machine. In addition, studies are also being conducted with lower body negative pressure (LBNP). There is some evidence that lowering the pressure around the lower body (using compact special equipment) will enhance the body’s ability to compensate (i.e., raise blood pressure and pulse when they fall too low). The LBNP countermeasure might be even more effective if the astronaut drinks moderate amounts of specially constituted salt water simultaneously.

If the cardiovascular problem is to be solved, not only is more work needed on these countermeasures, but also new ones must be found.

Musculoskeletal hazards

All astronauts returning from space have some degree of muscle wasting or atrophy, regardless of mission duration. Muscles at particular risk are those of the arms and legs, resulting in decreased size as well as strength, endurance and work capacity. Although the mechanism for these muscle changes is still ill-defined, a partial explanation is prolonged disuse; work, activity and movement in microgravity are almost effortless, since nothing has any weight. This may be a boon for astronauts working in space, but is clearly a liability when returning to a gravitational field, whether it be that of the moon or Earth. Not only could a weakened condition impede post-flight activities (including work on the lunar surface), it could also compromise rapid ground emergency escape, if required upon landing. Another factor is the possible requirement during EVA to do space vehicle repairs, which can be very strenuous. Countermeasures under study include in-flight exercises, electrical stimulation and anabolic medication (testosterone or testosterone-like steroids). Unfortunately, these modalities at best only retard muscle dysfunction.

In addition to muscle wasting, there is also a slow but inexorable loss of bone in space (about 300 mg per day, or 0.5% of total bone calcium per month) experienced by all astronauts. This has been documented by post-flight x rays of bones, particularly of those that bear weight (i.e., the axial skeleton). This is due to a slow but unremitting loss of calcium into the urine and faeces. Of great concern is the continuing loss of calcium, regardless of flight duration. Consequently, this calcium loss and bone erosion could be a limiting factor of flight, unless an effective countermeasure can be found. Although the precise mechanism of this very significant physiological aberration is not fully understood, it undoubtedly is due in part to the absence of gravitational forces on bone, as well as disuse, similar to muscle wasting. If bone loss were to continue indefinitely, particularly over long missions, bones would become so brittle that eventually there would be risk of fractures with even low levels of stress. Furthermore, with a constant flow of calcium into the urine via the kidneys, a possibility of renal stone formation exists, with accompanying severe pain, bleeding and infection. Clearly, any of these complications would be a very serious matter were they to occur in space.

Unfortunately, there are no known countermeasures that effectively prevent calcium loss during space flight. A number of modalities are being tested, including exercise (treadmill, bicycle ergometer and rowing machine), the theory being that such voluntary physical stresses would normalize bone metabolism, thereby preventing or at least ameliorating bone loss. Other countermeasures under investigation are calcium supplements, vitamins and various medications (such as diphosphonates—a class of medications that has been shown to prevent bone loss in patients with osteoporosis). If none of these simpler countermeasures prove to be effective, it is possible that the solution lies in artificial gravity that could be produced by continuous or intermittent rotation of the space vehicle. Although such motion could generate gravitational forces similar to that of the earth, it would represent an engineering “nightmare”, in addition to major add-on costs.

Neurovestibular hazards

More than half of the astronauts and cosmonauts suffer from space motion sickness (SMS). Although the symptoms vary somewhat from individual to individual, most suffer from stomach awareness, nausea, vomiting, headache and drowsiness. Often there is an exacerbation of symptoms with rapid head movement. If an astronaut develops SMS, it usually occurs within a few minutes to a few hours after launch, with complete remission within 72 hours. Interestingly, the symptoms sometimes recur after returning to the earth.

SMS, particularly vomiting, can not only be disconcerting to the crew members, it also has the potential to cause performance decrement in an astronaut who is ill. Furthermore, the risk of vomiting while in a pressure suit doing EVA cannot be ignored, as the vomitus could cause the life-support system to malfunction. It is for these reasons that no EVA activities are ever scheduled during the first 3 days of a space mission. If an EVA becomes necessary, for example, to do emergency repairs on the space vehicle, the crew would have to take that risk.

Much neurovestibular research has been directed toward finding a way to prevent as well as to treat SMS. Various modalities, including anti-motion-sickness pills and patches, as well as using pre-flight adaptation trainers such as rotating chairs to habituate astronauts, have been attempted with very limited success. However, in recent years it has been discovered that the antihistamine phenergan, given by injection, is an extremely effective treatment. Hence, it is carried onboard all flights and given as required. Its efficacy as a preventive has yet to be demonstrated.

Other neurovestibular symptoms reported by astronauts include dizziness, vertigo, dysequilibrium and illusions of self-motion and motion of the surrounding environment, sometimes making walking difficult for a short time post-flight. The mechanisms for these phenomena are very complex and are not completely understood. They could be problematical, particularly after a lunar landing following several days or weeks in space. As of now, there are no known effective countermeasures.

Neurovestibular phenomena are most likely caused by dysfunction of the inner ear (the semicircular canals and utricle-saccule), because of microgravity. Either erroneous signals are sent to the central nervous system or signals are misinterpreted. In any event, the results are the aforementioned symptoms. Once the mechanism is better understood, effective countermeasures can be identified.

Haematological hazards

Microgravity has an effect upon the body’s red and white blood cells. The former serve as a conveyor of oxygen to the tissues, and the latter as an immunological system to protect the body from invading organisms. Hence, any dysfunction could cause deleterious effects. For reasons not understood, astronauts lose approximately 7 to 17% of their red blood cell mass early in flight. This loss appears to plateau within a few months, returning to normal 4 to 8 weeks post-flight.

So far, this phenomenon has not been clinically significant, but, rather, a curious laboratory finding. However, there is clear potential for this loss of red blood cell mass to be a very serious aberration. Of concern is the possibility that with very long missions envisioned for the twenty-first century, red blood cells could be lost at an accelerated rate and in far greater quantities. If this were to occur, anaemia could develop to the point that an astronaut could become seriously ill. It is hoped that this will not be the case, and that the red blood cell loss will remain very small, regardless of mission duration.

In addition, several components of the white blood cell system are affected by microgravity. For example, there is an overall increase in the white blood cells, mainly neutrophils, but a decrease in lymphocytes. There is also evidence that some white blood cells do not function normally.

As of now, in spite of these changes, no illness has been attributed to these white blood cell changes. It is unknown whether or not a long mission will cause further decrease in numbers as well as further dysfunction. Should this occur, the body’s immune system would be compromised, making astronauts very susceptible to infectious disease, and possibly incapacitated by even minor illness that would otherwise easily be fended off by a normally functioning immunological system.

As with the red blood cell changes, the white blood cell changes, at least on missions of approximately one year, are not of clinical significance. Because of the potential risk of serious illness in-flight or post-flight, it is critical that research continue on the effects of microgravity on the haematological system.

Endocrinological hazards

During space flight, it has been noted that there are a number of fluid and mineral changes within the body due in part to changes in the endocrine system. In general, there is a loss of total body fluids, as well as calcium, potassium and calcium. A precise mechanism for these phenomena has eluded definition, although changes in various hormonal levels offer a partial explanation. To further confound matters, laboratory findings are often inconsistent among the astronauts who have been studied, making it impossible to discern a unitary hypothesis as to the cause of these physiological aberrations. In spite of this confusion, these changes have caused no known impairment of health of astronauts and no performance decrement in flight. What the significance of these endocrine changes are for very long flight, as well as the possibility that they may be harbingers of very serious sequelae, is unknown.

Acknowledgements: The authors would like to recognize the work of the Aerospace Medical Association in this area.

 

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Monday, 21 March 2011 15:29

Health Problems and Disease Patterns

Teachers comprise a large and growing segment of the workforce in many countries. For example, over 4.2 million workers were classified as preschool through high school teachers in the United States in 1992. In addition to classroom teachers, other professional and technical workers are employed by schools, including custodial and maintenance workers, nurses, food service workers and mechanics.

Teaching has not traditionally been regarded as an occupation that entails exposure to hazardous substances. Consequently, few studies of occupationally related health problems have been carried out. Nevertheless, school teachers and other school personnel may be exposed to a wide variety of recognized physical, chemical, biological and other occupational hazards.

Indoor air pollution is an important cause of acute illnesses in teachers. A major source of indoor air pollution is inadequate maintenance of heating, ventilation and air conditioning systems (HVAC). Contamination of HVAC systems can cause acute respiratory and dermatological illnesses. Newly constructed or renovated school buildings release chemicals, dusts and vapours into the air. Other sources of indoor air pollution are roofing, insulation, carpets, drapes and furniture, paint, caulk and other chemicals. Unrepaired water damage, as from roof leakage, can lead to the growth of micro-organisms in building materials and ventilation systems and the release of bioaerosols that affect the respiratory systems of teachers and students alike. Contamination of school buildings by micro-organisms can cause severe health conditions such as pneumonia, upper respiratory infections, asthma and allergic rhinitis.

Teachers who specialize in certain technical fields may be exposed to specific occupational hazards. For example, arts and craft teachers frequently encounter a variety of chemicals, including organic solvents, pigments and dyes, metals and metal compounds, minerals and plastics (Rossol 1990). Other art materials cause allergic reactions. Exposure to many of these materials is strictly regulated in the industrial workplace but not in the classroom. Chemistry and biology teachers work with toxic chemicals such as formaldehyde and other biohazards in school laboratories. Shop teachers work in dusty environments and may be exposed to high levels of wood dust and cleaning materials, as well as high noise levels.

Teaching is an occupation that is often characterized by a high degree of stress, absenteeism and burnout. There are many sources of teacher stress, which may vary with grade level. They include administrative and curriculum concerns, career advancement, student motivation, class size, role conflict and job security. Stress may also arise from dealing with children’s misbehaviours and possibly violence and weapons in schools, in addition to physical or environmental hazards such as noise. For example, desirable classroom sound levels are 40 to 50 decibels (dB) (Silverstone 1981), whereas in one survey of several schools, classroom sound levels averaged between 59 and 65 dB (Orloske and Leddo 1981). Teachers who are employed in second jobs after work or during the summer may be exposed to additional workplace hazards that can affect performance and health. The fact that the majority of teachers are women (three-fourths of all teachers in the United States are women) raises the question of how the dual role of worker and mother may affect women’s health. However, despite perceived high levels of stress, the rate of cardiovascular disease mortality in teachers was lower than in other occupations in several studies (Herloff and Jarvholm 1989), which could be due to lower prevalence of smoking and less consumption of alcohol.

There is a growing concern that some school environments may include cancer-causing materials such as asbestos, electromagnetic fields (EMF), lead, pesticides, radon and indoor air pollution (Regents Advisory Committee on Environmental Quality in Schools 1994). Asbestos exposure is a special concern among custodial and maintenance workers. A high prevalence of abnormalities associated with asbestos-related diseases has been documented in school custodians and maintenance employees (Anderson et al. 1992). The airborne concentration of asbestos has been reported higher in certain schools than in other buildings (Lee et al. 1992).

Some school buildings were built near high-voltage transmission power lines, which are sources of EMF. Exposure to EMF also comes from video display units or exposed wiring. Excess exposure to EMF has been linked to the incidence of leukaemia as well as breast and brain cancers in some studies (Savitz 1993). Another source of concern is exposure to pesticides that are applied to control the spread of insect and vermin populations in schools. It has been hypothesized that pesticide residues measured in adipose tissue and serum of breast cancer patients may be related to the development of this disease (Wolff et al. 1993).

The large proportion of teachers who are women has led to concerns about possible breast cancer risks. Unexplained increased breast cancer rates have been found in several studies. Using death certificates collected in 23 states in the United States between 1979 and 1987, the proportionate mortality ratios (PMRs) for breast cancer were 162 for White teachers and 214 for Black teachers (Rubin et al. 1993). Increased PMRs for breast cancer were also reported among teachers in New Jersey and in the Portland-Vancouver area (Rosenman 1994; Morton 1995). While these increases in observed rates have so far not been linked either to specific environmental factors or to other known risk factors for breast cancer, they have given rise to heightened breast cancer awareness among some teachers’ organizations, resulting in screening and early detection campaigns.

 

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Thursday, 24 March 2011 15:07

New Technology in Art

This article describes the basic health and safety concerns associated with the use of lasers, neon sculpture and computers in the arts. Creative artists often work very intimately with the technology, and in experimental ways. This scenario too often increases the risk of injury. The primary concerns are for eye and skin protection, for reducing the possibilities of electrical shock and for preventing exposure to toxic chemicals.

Lasers

Laser radiation may be hazardous to the eyes and skin of artists and audiences by both direct viewing and reflection. The degree of laser injury is a function of power. Higher-power lasers are more likely to cause serious injury and more hazardous reflections. Lasers are classified and labelled by their manufacturer in classes I to IV. Class I lasers exhibit no laser radiation hazard and Class IV are very dangerous.

Artists have used all laser classes in their work, and most use visible wavelengths. Besides the safety controls required of any laser system, artistic applications require special considerations.

In laser exhibits, it is important to isolate the audience from direct beam contact and scattered radiation, using plastic or glass enclosures and opaque beam stops. For planetariums and other indoor light shows, it is critical to maintain direct beam or reflected laser radiation at Class I levels where the audience is exposed. Class III or IV laser radiation levels must be kept at safe distances from performers and the audience. Typical distances are 3 m away when an operator controls the laser and 6 m away without continuous operator control. Written procedures are needed for set-up, alignment and testing of Class III and IV lasers. Required safety controls include warning in advance of energizing these lasers, key controls, fail-safe safety interlocks and manual reset buttons for Class IV lasers. For Class IV lasers, appropriate laser goggles should be worn.

Scanning laser art displays often used in the performing arts use rapidly moving beams that are generally safer since the duration of inadvertent eye or skin contact with the beam is short. Still, operators must employ safeguards to ensure exposure limits will not be exceeded if the scanning equipment fails. Outdoor displays cannot allow aircraft to fly through hazardous beam levels, or the illumination with greater than Class I levels of radiation of tall buildings or personnel in high-reach equipment.

Holography is the process of producing a three-dimensional photograph of an object using lasers. Most images are displayed off-axis from the laser beam, and intrabeam viewing is typically not a hazard. A transparent display case around the hologram can help reduce the possibilities of injury. Some artists create permanent images from their holograms, and many chemicals used in the development process are toxic and must be managed for accident prevention. These include pyrogallic acid, alkalis, sulphuric and hydrobromic acids, bromine, parabenzoquinone and dichromate salts. Safer substitutes are available for most of these chemicals.

Lasers also have serious non-radiological hazards. Most performance-level lasers use high voltages and amperage, creating significant risks of electrocution, particularly during design stages and maintenance. Dye lasers use toxic chemicals for the active lasing medium, and high-powered lasers may generate toxic aerosols, especially when the beam strikes a target.

Neon Art

Neon art uses neon tubes to produce lighted sculptures. Neon signage for advertising is one application. Producing a neon sculpture involves bending leaded glass to the desired shape, bombarding the evacuated glass tube at a high voltage to remove impurities from the glass tube, and adding small amounts of neon gas or mercury. A high voltage is applied across electrodes sealed into each end of the tube to give the luminous effect by exciting the gases trapped in the tube. To obtain a wider range of colours, the glass tube can be coated with fluorescent phosphors, which convert the ultraviolet radiation from the mercury or neon into visible light. The high voltages are achieved by using step-up transformers.

Electrical shock is a threat mostly when the sculpture is connected to its bombarding transformer to remove impurities from the glass tube, or to its electrical power source for testing or display (figure 1). The electrical current passing through the glass tube also causes the emission of ultraviolet light that in turn interacts with the phosphor-covered glass to form colours. Some near-ultraviolet radiation (UVA) may pass through the glass and present an eye hazard to those nearby; therefore, eyewear that blocks UVA should be worn.

Figure 1. Neon sculpture manufacture showing an artist behind a protective barrier.

ENT070F1

Fred Tschida

Some phosphors that coat the neon tube are potentially toxic (e.g., cadmium compounds). Sometimes mercury is added to the neon gas to create a particularly vivid blue colour. Mercury is highly toxic by inhalation and is volatile at room temperature.

Mercury should be added to the neon tube with great care and stored in unbreakable sealed containers. The artist should use trays to contain spillage, and mercury spill kits should be available. Mercury should not be vacuumed up, as this may disperse a mist of mercury through the vacuum cleaner’s exhaust.

Computer Art

Computers are used in art for a variety of purposes, including painting, displaying scanned photographic images, producing graphics for printing and television (e.g., on-screen credits), and for a variety of animated and other special effects for motion pictures and television. The latter is a rapidly expanding use of computer art. This can bring about ergonomic problems, typically due to repetitive tasks and uncomfortably arranged components. The predominant complaints are discomfort in the wrists, arms, shoulders and neck, and vision problems. Most complaints are of a minor nature, but disabling injuries such as chronic tendinitis or carpal tunnel syndrome are possible.

Creating with computers often involves long periods manipulating the keyboard or mouse, designing or fine tuning the product. It is important that computer users take a break away from the screen periodically. Short, frequent breaks are more effective than long breaks every couple of hours.

Regarding the proper arrangement of components and the user, design solutions for correct posture and visual comfort are the key. Computer work station components should be easy to adjust for the variety of tasks and people involved.

Eye strain may be prevented by taking periodic visual breaks, preventing glare and reflection and by placing the top of the monitor so that it is at eye level. Vision problems may also be avoided if the monitor has a refresh rate of 70 Hz, so that image flicker is reduced.

Many kinds of radiation effects are possible. Ultraviolet, visible, infrared, radio frequency and microwave radiation emissions from computer hardware are generally at or below normal background levels. The possible health effects of lower-frequency waves from the electrical circuitry and electronic components are not well understood. To date, however, no solid evidence identifies a health risk from exposure to the electromagnetic fields associated with computer monitors. Computer monitors do not emit hazardous levels of x rays.

 

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Thursday, 31 March 2011 17:52

Helicopters

The helicopter is a very special type of aircraft. It is used in every part of the world and serves a variety of purposes and industries. Helicopters vary in size from the smallest single-seat helicopters to giant heavy-lift machines with gross weights in excess of 100,000 kg, which is about the same size as a Boeing 757. The purpose of this article is to discuss some of the safety and health challenges of the machine itself, the different missions it are used for, both civilian and military, and the helicopter’s operating environment.

The helicopter itself presents some very unique safety and health challenges. All helicopters use a main rotor system. This is the lifting body for the machine and serves the same purpose as the wings on a conventional airplane. Rotor blades are a significant hazard to people and property because of their size, mass and rotational speed, which also makes them difficult to see from certain angles and in different lighting conditions.

The tail rotor is also a hazard. It is usually much smaller than the main rotor and turns at a very high rate, so it too is very difficult to see. Unlike the main rotor system, which sits atop the helicopter’s mast, the tail rotor is often near ground level. People should approach a helicopter from the front, in view of the pilot, to avoid coming into contact with the tail rotor. Extra care should be taken to identify or remove obstacles (such as bushes or fences) in a temporary or unimproved helicopter landing area. Contact with the tail rotor can cause injury or death as well as serious damage to the property or helicopter.

Many people recognize the characteristic slap sound of a helicopter’s rotor system. This noise is encountered only when the helicopter is in forward flight, and is not considered a health problem. The compressor section of the engine produces extremely loud noise, often in excess of 140 dBA, and unprotected exposure must be avoided. Hearing protection (ear plugs and a noise attenuating headset or helmet) should be worn when working in and around helicopters.

There are several other hazards to consider when working with helicopters. One is flammable or combustible liquids. All helicopters require fuel to run the engine(s). The engine and the main and tail rotor transmissions use oil for lubrication and cooling. Some helicopters have one or more hydraulic systems and use hydraulic fluid.

Helicopters build a static electric charge when the rotor system is turning and/or the helicopter is flying. The static charge will dissipate when the helicopter touches the ground. If an individual is required to grab a line from a hovering helicopter, as during logging, external lifts or rescue efforts, that person should let the load or line touch the ground before grabbing it in order to avoid a shock.


Helicopter operations
The uses of helicopters are numerous. The diversity of operations can be divided into two categories: civil and military.
Civil 

Rescue/air ambulance. The helicopter was originally designed with rescue in mind, and one of its most widespread uses is as an ambulance. These are often found at the scene of an accident or disaster (see figure 2). They can land in confined areas with qualified medical teams on board who care for the injured at the scene while en route to a medical facility. Helicopters are also used for non-emergency flights when speed of transport or patient comfort is required.

Offshore oil support. Helicopters are used to help supply offshore oil operations. They transport people and supplies between land and platform and between platforms.

Executive/personal transport. The helicopter is used for point-to-point transportation. This is usually done over short distances where geography or sluggish traffic conditions prevent rapid ground transportation. Corporations build helipads on company property to allow easy access to airports or to facilitate transportation between facilities.

Sightseeing. The use of helicopters in the tourist industry has seen continuous growth. The excellent view from the helicopter combined with its ability to access remote areas make it a popular attraction.

Law enforcement. Many police departments and governmental agencies use helicopters for this type of work. The helicopter’s mobility in crowded urban areas and remote rural areas makes it invaluable. The largest rooftop helipad in the world is at the Los Angeles Police Department.

Film operations. Helicopters are a staple in action movies. Other types of movies and film-based entertainment are filmed from helicopters.

News gathering. Television and radio stations employ helicopters for traffic spotting and news gathering. Their ability to land at the place where the news is happening makes them a valuable asset. Many of them are also equipped with microwave transceivers so they can send their stories, live, over fairly long distances, while en route.

Heavy lift. Some helicopters are designed to carry heavy loads at the end of external lines. Aerial logging is one application of this concept. Construction and oil exploration crews make extensive use of the helicopter’s capacity for lifting large or bulky objects into place.

Aerial application. Helicopters can be fitted with spray booms and loaded to dispense herbicides, pesticides and fertilizers. Other devices can be added that allow helicopters to fight fires. They can drop either water or chemical retardants.
 

Military

Rescue/aerial ambulance. The helicopter is used widely in humanitarian efforts. Many nations around the world have coast guards that engage in maritime rescue work. Helicopters are used to transport the sick and wounded from battle areas. Still others are sent to rescue or recover people from behind enemy lines.

Attack. Helicopters can be armed and used as attack platforms over land or sea. Weapon systems include machine guns, rockets and torpedoes. Sophisticated targeting and guidance systems are used to lock on to and destroy targets at longe range.

Transport. Helicopters of all sizes are used to transport people and supplies over land or sea. Many ships are equipped with helipads to facilitate offshore operations.


The Helicopter Operating Environment

The helicopter is used all over the world in a variety of ways (see, for example, figure 1 and figure 2). In addition, it is often working very near the ground and other obstructions. This requires constant vigilance from the pilots and those who work with or ride on the aircraft. By contrast, the fixed-wing aircraft environment is more predictable, since they fly (especially the commercial airplanes) primarily from airports whose airspace is tightly controlled.

Figure 1. H-46 helicopter landing in the Arizona, US, desert.

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Figure 2.  5-76A Cougar helicopter landing in field at accident site.

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The combat environment presents special dangers. The military helicopter also operates in a low-level environment and is subject to the same hazards. The proliferation of inexpensive, hand-carried, heat-seeking missiles represents another danger to rotorcraft. The military helicopter can use the terrain to hide itself or to mask its telltale signature, but when in the open it is vulnerable to small-arms fire and missiles.

Military forces also use night vision goggles (NVG) to enhance the pilot’s view of the area in low-light conditions. While the NVGs do increase the pilot’s ability to see, they have severe operating limitations. One major drawback is the lack of peripheral vision, which has contributed to mid-air collisions.

Accident Prevention Measures

Preventive measures can be grouped into several categories. Any one prevention category or item will not, in and of itself, prevent accidents. All of them must be used in concert to maximize their effectiveness.

Operational policies

Operational policies are formulated in advance of any operations. They are usually provided by the company with the operating certificate. They are crafted from governmental regulations, manufacturer’s recommended guidelines, industry standards, best practices and common sense. In general, they have proven to be effective in preventing incidents and accidents and include:

  • Establishment of best practices and procedures. Procedures are essential for accident prevention. When not used, such as in early helicopter ambulance operations, there were extremely high accident rates. In the absence of regulatory guidance, pilots attempted to support humanitarian missions at night and/or in poor weather conditions with minimal training and helicopters that were ill equipped for such flights, leading to accidents.
  • Crew resource management (CRM). CRM began as “cockpit resource management” but has since progressed to crew resource management. CRM is based on the idea that people in the crew should be free to discuss any situation among themselves to assure the successful completion of the flight. While many helicopters are flown by a single pilot, they are often working with other people who are either in the helicopter or on the ground. These people can provide information about the operation if consulted or allowed to speak. When such interaction occurs, CRM then becomes company resource management. Such collaboration is an acquired skill and should be taught to crews, company employees and others that work with and around helicopters.
  • Provision of a threat-free company environment. Helicopter operations can be seasonal. This means long, tiring days. Crews should be able to end their duty day without fear of recrimination. If there are other, similar, operational deficiencies, crews should be permitted to openly identify, discuss and correct them.
  • Physical hazards awareness. The helicopter presents an array of hazards. The aircraft’s dynamic components, its main and tail rotors, must be avoided. All passengers and crew members should be briefed on their location and on how to avoid coming into contact with them. The component’s surfaces should be painted to enhance their visibility. The helicopter should be positioned so that it is difficult for people to get to the tail rotor. Noise protection must be provided, especially to those with continuous exposure.
  • Training for abnormal conditions. Training is often limited, if available at all, to practising autorotations for engine-out conditions. Simulators can provide exposure to a much wider range of atypical conditions without exposing the crew or machine to the real condition.

 

Crew practices

  • Published procedures. One study of accidents has shown that, in more than half the cases, the accident would have been prevented had the pilot followed known, published procedures.
  • Crew resource management. CRM should be used.
  • Anticipating and avoiding known problems. Most helicopters are not equipped to fly in icing conditions and are prohibited from flying in moderate or severe turbulence, yet numerous accidents result from these circumstances. Pilots should anticipate and avoid these and other equally compromising conditions.
  • Special or non-standard operations. Pilots must be thoroughly briefed for such circumstances.

 

Support operations

The following are crucial support operations for the safe use of helicopters:

  • following published procedures
  • briefing all passengers prior to boarding the helicopter
  • keeping facilities free of obstructions
  • keeping facilities well lit for night operations.

 

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Monday, 21 March 2011 15:30

Environmental and Public Health Issues

Educational institutions are responsible for ensuring that their facilities and practices are in conformity with environmental and public health legislation and comply with accepted standards of care towards their employees, students and the surrounding community. Students are not generally covered under occupational health and safety legislation, but educational institutions must exercise diligence towards their students to at least the same degree as is required by legislation designed to protect workers. In addition, teaching institutions have a moral responsibility to educate their students on matters of personal, public, occupational and environmental safety which relate to them and to their activities.

Colleges and Universities

Large institutions such as college and university campuses may be compared to large towns or small cities in terms of the size of the population, geographic area, type of basic services required and complexity of activities being carried out. In addition to the occupational health and safety hazards found within such institutions (covered in the chapter Public and government services), there is a vast range of other concerns, relating to large populations living, working and studying in a defined area, that need to be addressed.

Waste management on campus is often a complex challenge. Environmental legislation in many jurisdictions requires stringent control of water and gas emissions from teaching, research and service activities. In certain situations external community concerns may require public relations attention.

Chemical and solid waste disposal programmes must take into consideration occupational, environmental and community health concerns. Most large institutions have comprehensive programmes for the management of the wide variety of wastes produced: toxic chemicals, radioisotopes, lead, asbestos, biomedical waste as well as trash, wet garbage and construction materials. One problem is the coordination of waste management programmes on campuses due to the large number of different departments, which often have poor communication with each other.

Colleges and universities differ from industry in the amounts and types of hazardous waste produced. Campus laboratories, for example, usually produce small amounts of many different hazardous chemicals. Methods of hazardous waste control can include neutralization of acids and alkalis, small-scale solvent recovery by distillation and “lab” packing, where small containers of compatible hazardous chemicals are placed in drums and separated by sawdust or other packing materials to prevent breakage. Since campuses can generate large quantities of paper, glass, metal and plastic waste, recycling programmes can usually be implemented as a demonstration of community responsibility and as part of the educational mission.

A few institutions located within urban areas may rely heavily upon external community resources for essential services such as police, fire protection and emergency response. The vast majority of medium-size and larger institutions establish their own public safety services to service their campus communities, often working in close cooperation with external resources. In many college towns, the institution is the largest employer and consequently may be expected to provide protection to the population which supports it.

Colleges and universities are no longer entirely remote or separate from the communities in which they are located. Education has become more accessible to a larger sector of society: women, mature students and the disabled. The very nature of educational institutions puts them at particular risk: a vulnerable population where the exchange of ideas and differing opinions is valued, but where the concept of academic freedom may not always be balanced with professional responsibility. In recent years educational institutions have reported more acts of violence toward educational community members, coming from the external community or erupting from within. Acts of violence perpetrated against individual members of the educational community are no longer extremely rare events. Campuses are frequent sites for demonstrations, large public assemblies, political and sports events where public safety and crowd control need to be considered. The adequacy of security and public safety services and emergency response and disaster recovery plans and capabilities needs to be constantly evaluated and periodically updated to meet community needs. Hazard identification and controls must be taken into consideration for sports programmes, field trips and a variety of sponsored recreational activities. Emergency medical service needs to be available even for off-campus activities. Personal safety is best managed through hazard reporting and education programmes.

Public health issues associated with campus life, such as control of communicable diseases, sanitation of food services and residence facilities, provision of fresh water, clean air and uncontaminated soil, must be addressed. Programmes for inspection, evaluation and control are required. Education of students in this regard is usually the responsibility of student service personnel, but occupational health and safety professionals are often involved. Education regarding sexually transmitted diseases, drug and alcohol abuse, blood-borne pathogens, stress and mental illness is particularly important in a campus community, where risky behaviour may increase the probability of exposure to associated hazards. Medical and psychological services must be available.

Elementary and Secondary Schools

Grade schools have many of the same environmental and public health issues as colleges and universities, only on a smaller scale. Often, however, schools and school districts do not have effective waste management programmes. A serious problem faced by many schools is the disposal of explosive ether and picric acid that have been stored in school laboratories for many years (National Research Council 1993). Attempts to dispose of these materials by unqualified personnel have caused explosions in several instances. One problem is that school districts can have many schools separated by several miles. This can create difficulties in centralizing hazardous waste programmes by having to transport hazardous waste on public roads.

 

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Thursday, 24 March 2011 15:10

Fibre and Textile Crafts

Contemporary fibre or textile artists use a wide range of processes, such as weaving, needlework, papermaking, leatherworking and so forth. These can be done by hand or aided by machines (see table 1). They may also use many processes for preparing fibres or finished textile, such as carding, spinning, dyeing, finishing and bleaching (see table 2). Finally the fibreworks or textiles may be painted, silk-screened, treated with photographic chemicals, scorched or otherwise modified. See separate articles in this chapter describing these techniques.

Table 1. Description of fibre and textile crafts.

Process

Description

Basketry

Basketry is the making of baskets, bags, mats, etc., by hand weaving, plaiting and coiling techniques using materials such as reeds, cane and sisal fibre. Knives and scissors are often used, and coiled baskets are often sewed together.

Batik

Batik involves the creating of dye patterns on fabric by applying molten wax to the fabric with a djanting to form a resist, dyeing the fabric and removing the wax with solvents or by ironing between newsprint.

Crocheting

Crocheting is similar to knitting except that a hook is used to loop threads into the fabric.

Embroidery

The embellishment of a fabric, leather, paper or other materials by sewing of designs worked in thread with a needle. Quilting comes under this category.

Knitting

Knitting is the craft of forming a fabric by interlocking of yarn in a series of connected loops using long hand or mechanized needles.

Lacemaking

Lacemaking involves the production of ornamental openwork of threads that have been twisted, looped and intertwined to form patterns. This can involve very fine and intricate hand stitching.

Leatherworking

Leather crafts involve two basic steps: cutting, carving, sewing and other physical processes; and cementing, dyeing and finishing the leather. The first can involve a variety of tools. The latter can involve the use of solvents, dyes, lacquers and such. For tanning, see the chapter Leather, fur and footwear.

Macrame

Macrame is the ornamental knotting of yarn into bags, wall hangings or similar materials.

Papermaking

Papermaking involves preparing the pulp and then making the paper. A variety of plants, wood, vegetables, used paper rags and so forth can be used. The fibres must be separated out, often by boiling in alkali. The fibres are washed and placed in a beater to complete preparation of the pulp. Then paper is made by trapping the pulp on a wire or fabric screen, and allowed to dry in the air or by being pressed between layers of felt. The paper can be treated with sizings, dyes, pigments and other materials.

Silk screen printing

See “Drawing, Painting and Printmaking”.

Weaving

Weaving uses a machine called a loom to combine two sets of yarn, the warp and the weft, to produce fabric. The warp is wound on large reels, called beams, which run the length of the loom. The warp yarns are threaded through the loom to form vertical parallel threads. The weft is fed from the side of the loom by bobbins. The loom shuttle carries the weft yarns across the loom horizontally under and above alternate warp threads. A starch sizing is used to protect warp threads from breaking during weaving. There are many types of looms, both hand-operated and mechanical.

 

Table 2. Description of fibre and textile processes.

Process      

Description

Carding

Process of cleaning and straightening fibres into parallel lines by combing it (by hand or by special machinery) and twisting the fibres into a rope-like form. This process can create large amounts of dust.

Spinning

A foot-pedal-operated spinning wheel is used to turn the spindle, which combines several fibres into twisted, elongated yarn.

Finishing

The woven fabric can be singed to remove projecting hairs, desized with enzymes, and scoured by boiling in alkali to remove fats and waxes.

Dyeing

Yarn or fabric can be dyed using a variety of types of dyes (natural, direct, acid, basic, disperse, fibre-reactive and more) depending upon the type of fabric. Many dyeing processes involve heating the dyebath to near boiling. Many dyeing assistants can be used, including acids, alkalis, salt, sodium hydrosulphite and, in the case of natural dyes, mordants such as urea, ammonium dichromate, ammonia, copper sulphate, and ferrous sulphate. Dyes are usually purchased in powder form. Some dyes may contain solvents.

Bleaching

Fabrics can be bleached with chlorine bleaches to remove colour.

 

No material is off limits for artists, who may use any of thousands of animal, vegetable or synthetic materials in their work. They gather materials such as weeds, vines or animal hair from the outdoors, or purchase products from suppliers who may have altered them by treating them with oils, fragrances, dyes, paints or pesticides (e.g., rat poison in twine or rope intended for agricultural use). Imported animal or vegetable materials that have been processed to eliminate disease carrying insects, spores or fungi are also used. Old rags, bones, feathers, wood, plastics or glass are among many other materials incorporated in fibre crafts.

Potential Sources of Health Hazards in the Fibre Arts

Chemicals

Health hazards in fibre or textile arts, as in any workplace, include air pollutants such as dusts, gases, fumes and vapours that are inherent in the materials or are produced in the work process, and can be inhaled or affect the skin. In addition to chemical hazards of dyes, paints, acids, alkalis, mothproofing agents and so on, fibre or textile materials may be contaminated with biological materials that can cause disease.

Vegetable dusts

Workers heavily exposed to dusts of raw cotton, sisal, jute and other vegetable fibres in industrial workplaces have developed various chronic lung problems such as “brown lung” (byssinosis), which begins with chest tightness and shortness of breath, and can be disabling after many years. Exposure to vegetable dusts in general may cause lung irritation or other effects such as asthma, hay fever, bronchitis and emphysema. Other materials associated with vegetable fibres, such as moulds, mildew, sizing materials and dyes, may also cause allergic or other reactions.

Animal dusts

Animal products used by fibre artists such as wool, hair, hides and feathers may be contaminated with bacteria, moulds, lice or mites that are capable of causing “Q” fever, mange, respiratory symptoms, skin rashes, anthrax, allergies and so on, if they are not treated or fumigated before use. Fatal cases of inhalation anthrax have occurred in craft weavers, including the 1976 death of a California weaver.

Synthetic materials

The effects of dusts of polyesters, nylon, acrylic, rayon and acetates are not well known. Some plastic fibres may release gas or components or residues which are left in the fabric after processing, as in the case of formaldehyde released by polyesters or permanent-press fabrics. Sensitive individuals have reported allergic responses in rooms or stores where these materials were present, and some have developed skin rashes after wearing clothing of these fabrics, even after repeated washings.

Heating, scorching or otherwise altering synthetic materials chemically may release potentially hazardous gases or fumes.

Physical Effects of Working with Fibres and Textiles

The physical characteristics of materials may affect the user. Rough, thorny or abrasive materials can cut or abrade skin. Glass fibres or stiff grasses or rattan can penetrate the skin and cause infections or rashes.

Much of fibre or fabric work is done while the worker is seated for prolonged periods, and involves repetitious motion of arms, wrists, hands and fingers, and often the entire body. This may produce pain and eventual repetitive strain injuries. Weavers, for example, can develop back problems, carpal tunnel syndrome, skeletal deformation from weaving in a squatting position on older types of looms (particularly in young children), hand and finger disorders (e.g., swollen joints, arthritis, neuralgia) from threading and tying knots, and eyestrain from poor lighting (figure 1). Many of the same problems can occur in other fibre crafts involving sewing, tying knots, knitting and so forth. Needlework crafts can also involve hazards of needle pricks.

Figure 1. Weaving with a hand loom.

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Lifting of large papermaking screens containing water-saturated pulp can cause possible back injuries due to the weight of the water and pulp.

Precautions

As with all work, the adverse effects depend upon the amount of time spent working on a project each day, the number of workdays, weeks or years, the quantity of work and the nature of the workplace, and the type of work itself. Other factors such as ventilation and lighting also affect the health of the artist or craftsperson. One or two hours a week spent at a loom in a dusty environment may not affect a person seriously, unless that person is highly allergic to dusts, but a prolonged period of work in the same environment over months or years may result in some health effects. However, even one episode of untrained lifting of a heavy object can cause injury to the spine.

Generally, for prolonged or regular work in fibre art or textiles:

  • Obtain and use only treated or fumigated animal or vegetable materials. Other materials should be cleaned or washed, and stored in closed containers to minimize dusts.
  • Damp mop or wipe work area surfaces frequently.
  • In many countries, manufacturers are required to provide information that describes the hazardous aspects of chemicals such as dyes, adhesives, paints or solvents in any product purchased, such as a manufacturer’s Material Safety Data Sheet (MSDS). Request such information.
  • Avoid eating, drinking or smoking in the work area.
  • Take frequent rest and exercise periods when work involves repetitive motion.
  • Modify work processes to reduce the need for excessive lifting or straining. For example, in papermaking use smaller screens or have another person assist in lifting the screen with the pulp.
  • Use exhaust ventilation for regular or prolonged use of dusty materials, spray painting, heating of wax or work with solvent-containing materials such as oil-based paints or permanent ink markers.
  • Avoid boiling acids and alkalis if possible. Wear gloves, goggles, face shield and protective apron.
  • Remember that dusts, gases and vapours travel throughout buildings and may affect others present, particularly infants, children, the aged and the chronically ill.
  • Consult an industrial hygienist or safety and health professional when planning a production workshop.

 

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Thursday, 24 March 2011 15:15

Ceramics

Foodware, sculpture, decorative tiles, dolls and other ceramic or clay items are made in both large and small professional studios and shops, classrooms in public schools, universities and trade schools, and in homes as a hobby or cottage industry. The methods can be divided into ceramics and pottery, although terminology can vary in different countries. In ceramics, objects are made by slip casting—pouring a slurry of water, clay and other ingredients into a mould. The clay objects are removed from the mould, trimmed and fired in a kiln. Some ware (bisque ware) is sold after this stage. Other types are decorated with glazes that are mixtures of silica and other substances which form a glass surface. In pottery, objects are formed from plastic clay, usually by hand-forming or wheel-throwing, after which they are dried and fired in a kiln. Objects may then be glazed. Slip cast ceramics usually are glazed with china paints, which are commercially produced in dry or liquid pre-packaged form (figure 1). Potters may glaze their ware with these commercial glazes or with glazes they compound themselves. All types of ware are produced, from terra cotta and earthenware, which are fired at low temperatures, to stoneware and porcelain, which are fired at high temperatures.

Figure 1.  Decorating a pot with China paints.

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Clay and Glaze Materials

All clays and glazes are mixtures of silica, aluminium and metallic minerals. These ingredients usually contain significant amounts of respirable-sized particles such as those in silica flour and ball clays. Clay bodies and glazes are composed of essentially the same types of minerals (see table 1, but glazes are formulated to melt at lower temperatures (have more flux) than the bodies on which they are applied. Lead is a common flux. Raw lead minerals such as galena and lead oxides derived from burning car battery plates and other scrap are used as fluxes, and have poisoned potters and their families in some developing countries. Commercially sold glazes for industrial and hobby use are more likely to contain lead and other chemicals which have been mixed and pre-fired into powdered frits. Glazes are formulated to mature in either oxidation or reduction firing (see below) and may contain metal compounds as colourants. Lead, cadmium, barium and other metals may leach into food when glazed ceramic wares are used.

Table 1. Ingredients of ceramic bodies and glazes.

Basic constituents

 

 

Clays (hydroaluminium silicates)

Alumina

Silica

Kaolins and other white clays

Red iron-rich clays

Fire clays

Ball clays

Bentonite

Aluminium oxide, corundum, usual source in glazes is from clays and feldspars

Quartz from flint, sand, diatomaceous earth; cristobalite from calcined silica or fired silica minerals

Other ingredients and some mineral sources

Fluxes

Opacifiers

Colourants

Sodium, potassium, lead, magnesium, lithium, barium, boron, calcium, strontium, bismuth

Tin, zinc, antimony, zirconium, titanium, fluorine, cerium, arsenic

Cobalt, copper, chrome, iron, manganese, cadmium, vanadium, nickel, uranium

Sources include oxides and carbonates of metals above, feldspars, talc, nepheline syenite, borax, colemanite, whiting, lead frits, lead silicates

Sources include oxides and carbonates of metals above, cryolite fluorspar, rutile, zirconium silicate

Sources include oxides, carbonates and sulphates of metals above, chromates, spinels and other metal complexes

 

Other special surface treatments include metallic lustre glazes containing tack oils and solvents such as chloroform, iridescent effects obtained by fuming metallic salts (usually chlorides of tin, iron, titanium or vanadium) onto surfaces during firing, and new paints containing plastic resins and solvents, which look like fired ceramic glazes when dry. Specially textured clay bodies may include fillers such as vermiculite, perlite and grog (ground fire brick).

Exposure to clay and glaze ingredients occurs during mixing, sanding and spray-applying glazes, and when grinding or chipping fired glaze imperfections from the bottoms of pottery or from kiln shelves (figure 2). Cleaning kiln shelves exposes workers to flint, kaolin and other kiln wash ingredients. Silica dust from fired kiln wash or bisque is more hazardous because it is in the cristobalite form. Hazards include: silicosis and other pneumoconioses from inhalation of minerals such as silica, kaolin, talc and fibrous amphibole asbestos in some talcs; toxicity from exposure to metals such as lead, barium and lithium; dermatitis from sensitizing metals such as chrome, nickel and cobalt; cumulative trauma disorders such as carpal tunnel syndrome (“potter’s thumb”) from wheel throwing; back injuries from digging clay, lifting 100-pound sacks of bulk minerals or from wedging (hand working clay to remove air bubbles); slips and falls on wet floors; shocks from electric pottery wheels and other equipment used in wet areas; allergies to moulds in clay; fungal and bacterial infections of nail beds and skin; and accidents with clay mixers, pug mills, blungers, slab rollers and the like.

Figure 2. Exposure to clay and glaze dusts while hand sanding a pot.

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Henry Dunsmore

Precautions: outlaw open lead burning; use substitutes for raw lead, lead frits, cadmium and asbestos-containing materials; isolate work from family areas and children; practice housekeeping and hygiene; control dust; use local exhaust ventilation for glaze spraying and dusty processes (figure 3); use respiratory protection; work with adequate rest periods; lift safely; guard machines; and use ground fault interrupters on wheels and all other electrical equipment.

Figure 3. Local exhaust ventilation for clay mixing.

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Michael McCann

Kiln Firing

Kilns vary from railroad-car size to a few cubic inches for firing test tiles and miniatures. They are heated with electricity or fuels such as gas, oil or wood. Electric kilns produce ware fired in primarily oxidizing atmospheres. Reduction firing is achieved by adjusting fuel/air ratios in fuel-fired kilns to create chemically reducing atmospheres. Firing methods include salt firing, raku (putting red-hot pots into organic matter such as damp hay to produce a smoky reduced clay body), climbing kilns (many-chambered wood or coal fired kilns built on hillsides), sawdust firing (kilns packed tight with pots and sawdust) and open-pit firing with many fuels including grass, wood and dung.

Primitive fuel-fired kilns are poorly insulated because they are usually made of fired clay, brick or mud. Such kilns can burn large amounts of wood and can contribute to fuel shortages in developing countries. Commercial kilns are insulated with refractory brick, castable refractory or ceramic fibre. Asbestos insulation is still found in older kilns. Refractory ceramic fibre is in very wide use in industry and hobby kilns. There are even small fibre kilns which are heated by putting them in home kitchen microwave ovens.

Kiln emissions include combustion products from fuels and from organic matter that contaminates clay and glaze minerals, sulphur oxides, fluorine and chlorine from minerals such as cryolite and sodalite, and metal fumes. Salt firing emits hydrochloric acid. Emissions are especially hazardous when fuels such as painted or treated wood and waste oils are burned. Hazards include: respiratory irritation or sensitization from aldehydes, sulphur oxides, halogens and other emissions; asphyxiation from carbon monoxide; cancer from inhalation of asbestos or ceramic fibre; eye damage from infrared radiation from glowing hot kilns; and thermal injury and burns.

Precautions: use clean-burning fuels; design fuel-efficient, well-insulated kilns; substitute refractory brick for asbestos or ceramic fibre; encapsulate or remove existing fibre insulation; locally vent indoor kilns; locate kilns in areas free of combustible materials; equip electric kilns with two automatic shut-offs; wear infrared-blocking goggles and gloves when handling hot objects.

 

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" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."

Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides