Tools are particularly important in construction work. They are primarily used to put things together (e.g., hammers and nail guns) or to take them apart (e.g., jackhammers and saws). Tools are often classified as hand tools and power tools. Hand tools include all non-powered tools, such as hammers and pliers. Power tools are divided into classes, depending on the power source: electrical tools (powered by electricity), pneumatic tools (powered by compressed air), liquid-fuel tools (usually powered by gasoline), powder-actuated tools (usually powered by an explosive and operated like a gun) and hydraulic tools (powered by pressure from a liquid). Each type presents some unique safety problems.
Hand tools include a wide range of tools, from axes to wrenches. The primary hazard from hand tools is being struck by the tool or by a piece of the material being worked on. Eye injuries are very common from the use of hand tools, as a piece of wood or metal can fly off and lodge in the eye. Some of the major problems are using the wrong tool for the job or a tool that has not been properly maintained. The size of the tool is important: some women and men with relatively small hands have difficulty with large tools. Dull tools can make the work much harder, require more force and result in more injuries. A chisel with a mushroomed head might shatter on impact and send fragments flying. It is also important to have the proper work surface. Cutting material at an awkward angle can result in a loss of balance and an injury. In addition, hand tools can produce sparks that can ignite explosions if the work is being done around flammable liquids or vapours. In such cases, spark-resistant tools, such as those made from brass or aluminium, are needed.
Power tools, in general, are more dangerous than hand tools, because the power of the tool is increased. The biggest dangers from power tools are from accidental start-up and slipping or losing one’s balance during use. The power source itself can cause injuries or death, for example, through electrocution with electrical tools or gasoline explosions from liquid-fuel tools. Most power tools have a guard to protect the moving parts while the tool is not in operation. These guards need to be in working order and not overridden. A portable circular saw, for example, should have an upper guard covering the top half of the blade and a retractable lower guard which covers the teeth while the saw is not operating. The retractable guard should automatically return to cover the lower half of the blade when the tool is finished working. Power tools often also have safety switches that shut off the tool as soon as a switch is released. Other tools have catches that must be engaged before the tool can operate. One example is a fastening tool that must be pressed against the surface with a certain amount of pressure before it will fire.
One of the main hazards of electrical tools is the risk of electrocution. A frayed wire or a tool that does not have a ground (that directs the electrical circuit to the ground in an emergency) can result in electricity running through the body and death by electrocution. This can be prevented by using double-insulated tools (insulated wires in an insulated housing), grounded tools and ground-fault circuit interrupters (which will detect a leak of electricity from a wire and automatically shut off the tool); by never using electrical tools in damp or wet locations; and by wearing insulated gloves and safety footwear. Power cords have to be protected from abuse and damage.
Other types of power tools include powered abrasive-wheel tools, like grinding, cutting or buffing wheels, which present the risk of flying fragments coming off the wheel. The wheel should be tested to make sure it is not cracked and will not fly apart during use. It should spin freely on its spindle. The user should never stand directly in front of the wheel during start-up, in case it breaks. Eye protection is essential when using these tools.
Pneumatic tools include chippers, drills, hammers and sanders. Some pneumatic tools shoot fasteners at high speed and pressure into surfaces and, as a result, present the risk of shooting fasteners into the user or others. If the object being fastened is thin, the fastener may go through it and strike someone at a distance. These tools can also be noisy and cause hearing loss. Air hoses should be well connected before use to prevent them from disconnecting and whipping around. Air hoses should be protected from abuse and damage as well. Compressed-air guns should never be pointed at anyone or against oneself. Eye, face and hearing protection should be required. Jackhammer users should also wear foot protection in case these heavy tools are dropped.
Gas-powered tools present fuel explosion hazards, particularly during filling. They should be filled only after they have been shut down and allowed to cool off. Proper ventilation must be provided if they are being filled in a closed space. Using these tools in a closed space can also cause problems from carbon monoxide exposure.
Powder-actuated tools are like loaded guns and should be operated only by specially trained personnel. They should never be loaded until immediately before use and should never left loaded and unattended. Firing requires two motions: bringing the tool into position and pulling the trigger. Powder-actuated tools should require at least 5 pounds (2.3 kg) of pressure against the surface before they can be fired. These tools should not be used in explosive atmospheres. They should never be pointed at anyone and should be inspected before each use. These tools should have a safety shield at the end of the muzzle to prevent the release of flying fragments during firing. Defective tools should be taken out of service immediately and tagged or locked out to make sure no one else uses them until they are fixed. Powder-actuated fastening tools should not be fired into material where the fastener could pass through and hit somebody, nor should these tools be used near an edge where material might splinter and break off.
Hydraulic power tools should use a fire-resistant fluid and be operated under safe pressures. A jack should have a safety mechanism to prevent it from being jacked up too high and should display its load limit prominently. Jacks have to be set up on a level surface, centred, bear against a level surface and apply force evenly to be used safely.
In general, tools should be inspected before use, be well-maintained, be operated according to the manufacturer’s instructions and be operated with safety systems (e.g., guards). Users should have proper PPE, such as safety glasses.
Tools can present two other hazards that are often overlooked: vibration and sprains and strains. Power tools present a considerable vibration hazard to workers. The most well-known example is chain-saw vibration, which can result in “white-finger” disease, where the nerves and blood vessels in the hands are damaged. Other power tools can present hazardous exposures to vibration for construction workers. As much as possible, workers and contractors should purchase tools where vibration has been dampened or reduced; anti-vibration gloves have not been shown to solve this problem.
Poorly designed tools can also contribute to fatigue from awkward postures or grips, which, in turn, can also lead to accidents. Many tools are not designed for use by left-handed workers or individuals with small hands. Use of gloves can make it harder to grip a tool properly and requires tighter gripping of power tools, which can result in excessive fatigue. Use of tools by construction workers for repetitive jobs can also lead to cumulative trauma disorders, like carpal tunnel syndrome or tendinitis. Using the right tool for the job and choosing tools with the best design features that feel most comfortable in the hand while working can assist in avoiding these problems.