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Course 810 - Hand and Power Tool Safety

Safety guides and audits to make your job as a safety professional easier

Portable Abrasive Wheel and Pneumatic Tools


Portable Abrasive Wheel Tools

One of the most common tools found in any shop, the portable grinder is incredibly useful for grinding and finishing material of all shapes and sizes.

The hazards associated with portable grinders are similar to those of pedestal or bench grinders. The rotating abrasive stone can cause severe abrasions and cuts. There’s also the potential or the abrasive stone to shatter and kickback from the spindle end. Other hazards such as flying fragments and sparks are present during grinding.

When using a powered grinder:

  • Always use eye or face protection.
  • Turn off the power when not in use.
  • Never clamp a hand-held grinder in a vice.


double insulated

Portable grinders usually come with the manufacturer’s safety guard covering most of the wheel.

Exposure to the wheel should not exceed a maximum angle of 180 degrees, and the top half must be enclosed at all times. The guard should be mounted so it maintains proper alignment with the wheel.

Abrasive wheel tools must be equipped with guards that:

  1. Cover the spindle end, nut, and flange projections.
  2. Maintain proper alignment with the wheel.
  3. Do not exceed the strength of the fastenings.

Vertical “right angle” grinders should have a 180-degree guard between the operator and wheel. The guard should be adjusted so that pieces of a broken wheel will be deflected away from the operator.

Cup wheel grinders should be guarded as described above or with special “revolving cup guards,” which mount behind the wheel and turn with it.


All abrasive wheels must be inspected and “ring-tested” before mounting to ensure that they are free from cracks or other defects. The spindle speed of the machine also must be checked before mounting the wheel to ensure it does not exceed the maximum operating speed marked on the wheel. Always follow the manufacturer’s recommendations.

To test the wheel, do the following:

  • Tap the wheel with a light, non-metallic instrument.
  • A stable and undamaged wheel will give a clear metallic tone or ring.
  • If the wheel sounds cracked or dead, it must not be used because it could fly apart when operated. Dispose of it and use another wheel.
Grinder Safety-Graphic Video

Wheels (Continued)

To prevent an abrasive wheel from cracking, it must fit freely on the spindle.

  • The spindle nut must be tightened enough to hold the wheel in place without distorting the flange.
  • Always follow the manufacturer’s recommendations.
  • Ensure that the spindle speed of the machine will not exceed the maximum operating speed marked on the wheel.

An abrasive wheel may disintegrate or explode during start-up. To make sure you do not get injured during startup, do the following:

Grinder Safety-Graphic Video
  • Allow the tool to come up to operating speed prior to grinding or cutting.
  • Never stand in the plane of rotation of the wheel as it accelerates to full operating speed.

Abrasive wheels must be supplied with sufficient power to maintain the spindle speed at safe levels under all conditions. Do not run a wheel or blade faster than its maximum rated capacity.

Concrete Grinders and Cutters


Construction workers who perform concrete grinding and cutting may breathe dust that contains respirable crystalline silica (RCS).

Grinding/polishing Dry grinding and polishing is the method most commonly used in the industry. A NIOSH study found that workers dry grinding concrete to smooth poured concrete surfaces were exposed to high levels of dust containing RCS, ranging from 35 to 55 times the NIOSH recommended exposure limit (REL). Wet polishing uses water to cool the diamond abrasives and eliminate grinding dust.

Concrete cutting is a process of controlled sawing, drilling and removing concrete. Skilled operators use special saws to cut concrete and asphalt. As with grinding, dry cutting is most often used. Careful selection of saw blades can help reduce exposure. Diamond saw blades produce less dust and require less water which make them better than abrasive saw blades to cut.

The concrete saw should have a local exhaust ventilation (LEV) system, which can capture the majority of dust emitted during the cutting operation. When operating, the operator should always wear personal protective equipment (PPE).


A local exhaust ventilation (LEV) system can be used to reduce the exposure to silica dust. The LEV system consists of a grinder equipped with a ventilation shroud, a length of flexible hose, and a portable electric vacuum cleaner that acts as a fan and dust collector for the ventilation system. See illustration above.

Real World Accident

An employee was using a grinder to grind a metal pin, when the pin became jammed and drawn into the space between the tool rest and the spinning grinding wheel. The employee’s left index finger was also drawn into and against the abrasive wheel, and it was amputated. He was hospitalized. The distance between the tool rest and the abrasive wheel is not known. It is also not known whether the rest was secured in that position. At the time of the accident, the grinder's tongue guard was adjusted to a position 0.875 inches from the wheel. (Source: OSHA)

Pneumatic Tools

Pneumatic tools are powered by compressed air and include chippers, drills, hammers, and sanders.

There are several dangers associated with the use of pneumatic tools. First and foremost is the danger of getting hit by one of the tool’s attachments or by some kind of fastener the worker is using with the tool. Be sure to know and comply with the following best practices when working with pneumatic tools:

  • Check to see that the tools are fastened securely to the air hose to prevent them from becoming disconnected. A short wire or positive locking device attaching the air hose to the tool must also be used and will serve as an added safeguard.
  • To reduce pressure in case of hose failure, make sure a safety excess flow valve is installed if an air hose is more than 1/2-inch (12.7 millimeters) in diameter.
  • Take the same precautions with an air hose that are recommended for electric cords, because the hose is subject to the same kind of damage or accidental striking, and because it also presents tripping hazards.
  • Install a safety clip or retainer to prevent attachments such as chisels on a chipping hammer from being ejected during tool operation.
  • Eye protection is required. Head and face protection is also recommended for employees working with pneumatic tools.
  • Screens must also be set up to protect nearby workers from being struck by flying fragments around chippers, riveting guns, staplers, or air drills.
  • Compressed air guns should never be pointed toward anyone.
  • Workers should never “dead-end,” or block the tip of the air gun against themselves or anyone else. A chip guard must be used when compressed air is used for cleaning.
  • Do not use compressed air to clean clothing. Cleaning clothing with compressed air can increase the oxygen level within clothing fabric to the point that the clothing becomes extremely flammable. The result may be a fatal injury due to burns.

Noise is another hazard associated with pneumatic tools. Working with noisy tools such as jackhammers requires proper, effective use of appropriate hearing protection.

Check out this short audio clip by Dan Clark of the give safety tips when working with compressed air.

Nail Gun Safety

Nail Guns

Nail guns are used every day on many construction jobs. They boost productivity but also cause tens of thousands of serious injuries each year. Injuries resulting from the use of nail guns hospitalize more construction workers than any other tool-related injury. When they do occur, these injuries are often not reported or given proper medical treatment. One study found that two out of five residential carpenter apprentices experienced a nail gun injury over a four-year period.

General safety guidelines

  • Review the owner’s manual carefully with all operators.
  • Observe each employee demonstrating safe operating procedures.
  • Always wear safety glasses.
  • Do not touch the trigger unless firing the tool against the work piece.
  • Use extreme caution when using an air tool around other workers.
  • Never point the tool at anyone. Treat the tool like a firearm and assume it’s loaded.
  • Disconnect the air hose before clearing a jam or making adjustments.
  • Use manufacturer’s specified pressures for the tool.
  • Keep your free hand safely out of the way of the tool.
  • Secure the hose when working on scaffolds to prevent the weight of the hose from dragging the tool off the scaffold if you set the tool down.

Trigger Selection

Safe Handling of Nail Guns-Graphic

Research has identified that the risk of a nail gun injury is twice as high when using a multi-shot contact trigger as when using a single-shot sequential trigger nailer.

Sequential mode and bump mode are the two basic trigger mechanisms used in pneumatic nailers and staplers. It is important to understand the differences between the two triggers in order to prevent injuries. To find out whether your nail gun is a sequential trigger or bump trigger model, fire a nail as usual and keep the trigger depressed. Lift the nail gun and carefully press its nose against the work surface again. If the gun fires a second nail, you have a bump trigger model. If the gun doesn’t fire, you have the safer sequential trigger model.

  • Sequential mode trigger: In the sequential mode, also known as a restrictive trigger or operating in the trigger fire mode, you must first press the nail gun firmly against the workpiece and then press the trigger.
Safe Handling of Nail Guns-Graphic

One nail is fired and you must release the trigger before you can begin the next nailing cycle.

  • Bump mode trigger: In the bump mode trigger, also known as dual- action, bottom fire, or contact trip, you must press the trigger before you bring the nail gun into contact with the workpiece. Each time you press the nailer against the workpiece, a nail is fired and a nailing cycle begins. You must keep the trigger pulled while moving the tool along the work surface with a bouncing motion, depressing the safety element where you want to drive a nail or staple. By repeatedly “bumping” the nail gun against the workpiece, you can rapidly fire any number of nails. (Source: OR-OSHA)

Pneumatic tools that shoot nails, rivets, staples, or similar fasteners and operate at pressures more than 100 pounds per square inch (6,890 kPa) must be equipped with a special device to keep fasteners from being ejected, unless the muzzle is pressed against the work surface.

To get more information read the Department of Labor’s Nail Gun Safety – A Guide for Construction Contractors and the CDC’s Straight Talk About Nail-Gun Safety.



Four potentially serious safety and health hazards exist when using pneumatic jackhammers:

  • excessive noise
  • excessive vibration
  • exposure to dust
  • being struck by flying objects

Use of heavy jackhammers can cause fatigue and strains. Heavy rubber grips reduce these effects by providing a secure handhold. Workers operating a jackhammer must wear safety glasses and safety shoes that protect them against injury if the jackhammer slips or falls. A face shield also should be used.

Silica hazard: Construction workers are potentially exposed to hazardous dust containing respirable crystalline silica (RCS) when using jackhammers to break concrete pavement. NIOSH found such exposures could be reduced by using a water-spray attachment. This low-flow, water-spray control suppressed and reduced dust exposures by 70%–90%. (Source: NIOSH)

Safe Handling of Nail Guns-Graphic

Real World Accident

Two employees were using jackhammers to break up a 240-square-meter, 150-millimeter-thick concrete pad located in the center of a round condominium. The employees had used the jackhammers to break the concrete near a high voltage conduit line and were using hammers to break the concrete from around the conduit. One of the employees used a jackhammer to break the concrete over the conduit. The jackhammer slipped, and the employee lost his balance. He fell to the ground, and the jackhammer broke through the concrete and conduit and contacted the three-phase line. The bit of the jackhammer cut all three AWG #2 stranded copper conductors and causing an electrical fault. The ensuing electric arc burned the employee who had been using the jackhammer. The electrical fault also damaged the control cabinet in the fire pump room. The injured employee was treated at a hospital for burns to his face and released the same day.

Abrasive Blasting Tools

safe work

Abrasive blasting may have several hazards associated with it at any given time. Abrasive blasting is more commonly known as sandblasting since silica sand has been a commonly used material as the abrasive, although not the only one always used.

Abrasive blasting entails accelerating a grit of sand-sized particles with compressed air to provide a stream of high-velocity particles used to clean metal objects such as steel structures or provide a texture to poured concrete. This process typically produces a large amount of dust from the abrasive, anything on the substrate being abraded, and/or the substrate itself.

Safe Work Practices

Using good work practices workers will reduce the risk of exposure to toxic air contaminants and other safety and health hazards associated with abrasive blasting. Safe work practices include all of the following:

  • use vacuums equipped with High Efficiency Particulate Air (HEPA) filters or wet methods when removing accumulated dust
  • schedule blasting when the least number of people would be exposed
  • perform blasting in a specified location that is as far away as possible from other employees
  • stop other work and clearing people away while blasting is taking place
  • cleaning up paint chips, dust, and used abrasive daily or as soon as possible after blasting has finished
  • avoid blasting in windy conditions
  • post warning signs to mark the boundaries of work areas contaminated with blasting dust and alerting employees to the hazard and any required PPE

Spray Guns

One of the most frequent types of spray operations is spray painting, with spray booths as a common engineering control used to protect workers. Spray booths serve two main purposes:

  1. to protect the health of the painter
  2. to reduce fire and explosion hazards

All spraying areas must be provided with mechanical ventilation adequate to remove flammable vapors, mists, or powders to a safe location and to confine and control combustible residues so that life is not endangered.

Mechanical ventilation must be kept in operation at all times while spraying operations are being conducted and for a sufficient time thereafter to allow vapors from drying coated articles and drying finishing material residue to be exhausted.

Personal Hygiene

spray guns

Employers must require that employees use proper personal hygiene practices. These practices are an important control measure for protecting employees from exposure to hazardous contaminants generated during abrasive blasting. Some contaminants, such as lead, are hazardous when inhaled or ingested. Others, such as beryllium, may be hazardous through inhalation and skin contact. Good personal hygiene practices to limit exposure to abrasive blasting dust include the following:

  • Prohibit eating, drinking, using tobacco products, or applying cosmetics in abrasive blasting areas.
  • Wash hands and face before eating, drinking, smoking, or applying cosmetics.
  • Shower before leaving the worksite.
  • Change into clean clothing before leaving the worksite.
  • Park cars where they will not be contaminated with abrasive blasting dust.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Which of the following portable tools is most likely going to expose workers to flying objects, abrasions, and cuts?

2. Exposure to the grinder wheel should not exceed a maximum angle of _____.

3. What is the most common hazard when using pneumatic tools?

4. Which of the following is not listed as a serious hazard when working with pneumatic jackhammers?

5. What is a potentially fatal hazard associated with cleaning work clothes with compressed air?

Have a safe day!

Important! You will receive an "error" message unless all questions are answered.