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

Safety Hazards


Employers must assess tasks to identify potential worksite hazards and provide and ensure that workers use appropriate personal protective equipment (PPE) as stated in 29 CFR 1910.132, Personal Protective Equipment General Requirements.

Employers must require workers to use appropriate hand protection when hands are exposed to hazards such as sharp instruments and potential thermal burns. Examples of PPE which may be selected include using oven mitts when handling hot items and steel mesh or cut-resistant gloves when handling or sorting sharp instruments as stated in 29 CFR 1910.138, Hand Protection.

Autoclaves and Sterilizers

Autoclaves and Sterilizers

An autoclave is used in laboratories to sterilize equipment and supplies. They pose several hazards to laboratory workers, including:

  • Burns from pressurized heat and steam. When opening the door, be sure to keep face, body and hands away from escaping heat and steam.
  • Explosions if the door seals fail during operation. Pressure and heat in the autoclave’s chamber can escape causing serious injury.
  • Ergonomic lifting injuries when moving equipment. Get help when moving heavy equipment.
  • When handling or sorting hot sterilized items or sharp instruments, cuts can occur. Be sure to be careful when removing them from autoclaves or sterilizers.

1. Keep your face, body and hands away from escaping heat and steam when opening the door of a/an _____.

a. refrigerator
b. microwave oven
c. autoclave
d. centrifuge

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Due to the high speed at which they operate, centrifuges have great potential for injuring users if not operated properly. Unbalanced centrifuge rotors can result in injury, even death. Sample container breakage can generate aerosols that may be harmful if inhaled.

The majority of all centrifuge accidents are the result of user error. To avoid injury, workers should follow the manufacturer’s operating instructions for each make and model of centrifuge they use.

Follow these steps for the safe operation of centrifuges:

  • Ensure centrifuge bowls and tubes are dry.
  • Ensure the spindle is clean.
  • Use matched sets of tubes, buckets and other equipment.
  • Always use safety centrifuge cups to contain potential spills and prevent aerosols.
  • Inspect tubes or containers for cracks or flaws before using them.
  • Avoid overfilling tubes or other containers (e.g., in fixed angle rotors, centrifugal force may drive the solution up the side of the tube or container wall).
  • Ensure the rotor is properly seated on the drive shaft.
  • Make sure tubes or containers are properly balanced in the rotor.
  • Only check O-rings on the rotor if you are properly trained.
  • Apply vacuum grease in accord with the manufacturer’s guidelines.
  • Do not exceed the rotor’s maximum run speed.
  • Close the centrifuge lid during operation.
  • Make sure the centrifuge is operating normally before leaving the area.
  • Make sure the rotor has come to a complete stop before opening the lid.

Employers should instruct workers when centrifuging infectious materials that they should wait 10 minutes after the centrifuge rotor has stopped before opening the lid. Workers should also be trained to use appropriate decontamination and cleanup procedures for the materials being centrifuged if a spill occurs and to report all accidents to their supervisor immediately.

2. Which of the following physical hazards can cause laboratory worker injury or even death?

a. Unbalanced centrifuge rotors
b. Misaligned microscope
c. Mechanical pipetting
d. Defective enclosures

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Compressed Gases

Compressed Gases

Within laboratories, compressed gases are usually supplied either through fixed piped gas systems or individual cylinders of gases. Compressed gases contained in cylinders vary in chemical properties, ranging from inert and harmless to toxic and explosive. The high pressure of the gases constitutes a serious hazard in the event that gas cylinders sustain physical damage and/or are exposed to high temperatures.

Compressed gases can be toxic, flammable, oxidizing, corrosive, or inert. Leakage of any of these gases can be hazardous in the following ways:

  • Leaking inert gases (e.g., nitrogen) can quickly displace air in a large area creating an oxygen-deficient atmosphere;
  • Toxic gases can create poisonous atmospheres; and
  • Flammable (oxygen) or reactive gases can result in fire and exploding cylinders.

In addition, there are hazards from the pressure of the gas and the physical weight of the cylinder, including:

  • A gas cylinder falling over can break containers and crush feet.
  • The gas cylinder can itself become a missile if the cylinder valve is broken off.

Laboratories must include compressed gases in their inventory of chemicals in their Chemical Hygiene Plan.

Store, handle, and use compressed gases in accord with OSHA’s Compressed Gases Standard (29 CFR 1910.101) and Pamphlet P-1 from the Compressed Gas Association. Be sure to adhere to the following:

  • All cylinders whether empty or full must be stored upright.
  • Secure cylinders of compressed gases. Cylinders should never be dropped or allowed to strike each other with force.
  • Transport compressed gas cylinders with protective caps in place and do not roll or drag the cylinders.

3. Which of the following can quickly displace air in a large area creating an oxygen-deficient atmosphere in the laboratory?

a. Compressed gases
b. Toxic fumes
c. Leaking inert gases (e.g., nitrogen)
d. Flammable (oxygen) or reactive gases

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Cryogens and Dry Ice

Cryogens and Dry Ice

Cryogens, substances used to produce very low temperatures [below -153°C (-243°F)], such as liquid nitrogen (LN2) which has a boiling point of -196°C (-321°F), are commonly used in laboratories. Although not a cryogen, solid carbon dioxide or dry ice which converts directly to carbon dioxide gas at -78°C (-109°F) is also often used in laboratories. Shipments packed with dry ice, samples preserved with liquid nitrogen, and, in some cases, techniques that use cryogenic liquids, such as cryogenic grinding of samples, present potential hazards in the laboratory.

Overview of Cryogenic Safety Hazards

The safety hazards associated with the use of cryogenic liquids are categorized as follows:

  1. Cold contact burns. Liquid or low-temperature gas from any cryogenic substance will produce effects on the skin similar to a burn.
  2. Asphyxiation. Degrees of asphyxia will occur when the oxygen content of the working environment is less than 20.9% by volume. This decrease in oxygen content can be caused by a failure/leak of a cryogenic vessel or transfer line and subsequent vaporization of the cryogen. Effects from oxygen deficiency become noticeable at levels below approximately 18% and sudden death may occur at approximately 6% oxygen content by volume.
  3. Explosion – Pressure. Heat flux into the cryogen from the environment will vaporize the liquid and potentially cause pressure buildup in cryogenic containment vessels and transfer lines. Adequate pressure relief should be provided to all parts of a system to permit this routine outgassing and prevent explosion.
  4. Explosion – Chemical. Cryogenic fluids with a boiling point below that of liquid oxygen are able to condense oxygen from the atmosphere. Repeated replenishment of the system can thereby cause oxygen to accumulate as an unwanted contaminant. Similar oxygen enrichment may occur where condensed air accumulates on the exterior of cryogenic piping. Violent reactions (e.g., rapid combustion or explosion) may occur if the materials that make contact with the oxygen are combustible.

Whenever working with cryogenic fluids, be sure to use the following personal protective equipment:

  • Face shield or safety goggles. Eye protection is required at all times when working with cryogenic fluids. When pouring a cryogen, working with a wide-mouth Dewar flask or around the exhaust of cold boil-off gas, use of a full face shield is recommended.
  • Safety gloves. Hand protection is required to guard against the hazard of touching cold surfaces. It is recommended that Cryogen Safety Gloves be used by the worker.
  • Long-sleeved shirts, lab coats, and aprons. Chemical-resistant sleeves should be used to provide additional protection. To protect against the risk of a splash hazard, consider using a chemical-resistant apron, such as those made from rubber, neoprene or PVC (depending on compatibility). Lab coat materials may be made of materials for limited reuse, or disposable one time use. If chemicals penetrate the coat or sleeve material, take it off and be sure to wash any affected area of your skin for 15 minutes.

For more information on laboratory PPE, see Lawrence Berkeley National Laboratory (Berkeley Lab) PPE requirements, Chapter 19 .

4. Which of the following PPE is recommended when pouring a cryogen?

a. Full face shield
b. Goggles
c. Safety glasses
d. N95 face mask

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In the laboratory, there is the potential for workers to be exposed to electrical hazards including electric shock, electrocutions, fires and explosions.

Damaged electrical cords can lead to possible shocks or electrocutions. A flexible electrical cord may be damaged by door or window edges, by staples and fastenings, by equipment rolling over it, or simply by aging.

The potential for possible electrocution or electric shock or contact with electrical hazards can result from a number of factors, including the following:

  • Faulty electrical equipment/instrumentation or wiring;
  • Damaged receptacles and connectors; and
  • Unsafe work practices.

Employers are responsible for complying with OSHA’s electrical safety standard, 1910 Subpart S - Electrical. This standard is comprehensive and addresses electrical safety requirements for the practical safeguarding of workers in their workplaces, including:

  • Electrical equipment must be free from recognized hazards.
  • Listed or labeled equipment must be used or installed in accord with any instructions included in the listing or labeling.
  • Sufficient access and working space must be provided and maintained around all electrical equipment operating at less than or equal to 600 volts to permit ready and safe operation and maintenance of such equipment;
  • Ensure that all electrical service near sources of water is properly grounded.
  • Repair all damaged receptacles and portable electrical equipment before placing them back into service.
  • Ensure that workers do not plug or unplug equipment when their hands are wet.
  • Follow requirements for Hazardous Classified Locations, 29 CFR 1910.307. This section covers the requirements for electric equipment and wiring in locations that are classified based on the properties of the flammable vapors, liquids or gases, or combustible dusts or fibers that may be present therein and the likelihood that a flammable or combustible concentration or quantity is present.
  • Only "Qualified Persons," as defined by OSHA in 29 CFR 1910.399, are to work on electrical circuits/systems.
  • Workers must be trained to know the locations of circuit breaker panels that serve their lab area.

5. OSHA requires that employees who work on electrical circuits/systems must be _____.

a. Qualified Persons
b. Competent Persons
c. Maintenance Persons
d. Safety Professionals

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Laboratory workers performing service or maintenance on equipment may be exposed to injuries from the unexpected energization, startup of the equipment, or release or stored energy in the equipment.

OSHA's Control of Hazardous Energy Standard, 29 CFR 1910.147, commonly referred to as the "Lockout/Tagout" Standard, requires employers to adopt and implement safe practices and procedures to:

  • shut down equipment,
  • isolate it from its energy source(s), and
  • prevent the release of potentially hazardous energy while maintenance and servicing activities are being performed.

The standard covers servicing and maintenance of machines and equipment in which the "unexpected" energization or startup of the machines or equipment, or release of stored energy could cause injury to workers.

The term "unexpected" also covers situations in which the servicing and/or maintenance is performed during ongoing normal production operations if:

  • a worker is required to remove or bypass machine guards or other safety devices, or
  • a worker is required to place any part of his or her body into a point of operation or into an area on a machine or piece of equipment where work is performed, or into the danger zone associated with the machine’s operation.

Unexpected and unrestricted release of hazardous energy can occur if:

  • all energy sources are not identified;
  • provisions are not made for safe work practices with energy present; or
  • deactivated energy sources are reactivated, mistakenly, intentionally, or accidentally, without the maintenance worker’s knowledge.

Employers should develop, implement and enforce effective procedures for controlling hazards to ensure worker safety during maintenance.

6. What procedure is required to remove or bypass machine guards or other safety devices to perform maintenance?

a. Pre-job evaluation
b. Employee notification
c. Lockout/Tagout
d. Electrical reset

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Safety Equipment in the Lab
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Fire is the most common serious hazard in a typical laboratory. Small bench-top fires in laboratory spaces are not uncommon. Large laboratory fires are rare.

While proper procedures and training can minimize the chances of an accidental fire, laboratory workers should still be prepared to deal with a fire emergency. In dealing with a laboratory fire, all containers of infectious materials should be placed into autoclaves, incubators, refrigerators, or freezers for containment.

However, the risk of severe injury or death is significant because fuel load and hazard levels in labs are typically very high. Laboratories, especially those using solvents in any quantity, have the potential for flash fires, explosion, rapid spread of fire, and high toxicity of products of combustion (heat, smoke, and flame).

Fire Safety Training

Employers should train workers to remember the “PASS” rule for fire extinguishers.

PASS summarizes the operation of a fire extinguisher.

P – Pull the pin.

A – Aim extinguisher nozzle at the base of the fire.

S – Squeeze the trigger while holding the extinguisher upright.

S – Sweep the extinguisher from side to side; cover the fire with the spray.

The two most common types of extinguishers in the chemistry laboratory are pressurized dry chemical (Type BC or ABC) and carbon dioxide. In addition, you may also have a specialized Class D dry powder extinguisher for use on flammable metal fires.

Water-filled extinguishers are not acceptable for laboratory use.

7. What is the most common serious hazard in a typical laboratory?

a. Fire
b. Falling
c. Being cut
d. Getting infected

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Fire Safety Training (Continued)

Emergency Action Plans
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Employers should train workers on appropriate procedures in the event of a clothing fire.

  • If the floor is not on fire, STOP, DROP and ROLL to extinguish the flames or use a fire blanket or a safety shower if not contraindicated (i.e., there are no chemicals or electricity involved).
  • If a coworker’s clothing catches fire and he/she runs down the hallway in panic, tackle him/her and smother the flames as quickly as possible, using appropriate means that are available (e.g., fire blanket, fire extinguisher).

Employers should also train laboratory workers on the Laboratory Emergency Action Plan (see OSHAcademy Course 717: Emergency Action Plans) and to do the following to prevent fires:

  • Use only the minimum quantities of chemicals needed for laboratory processes and observe restrictions on equipment (i.e., keeping solvents only in an explosion-proof refrigerator).
  • Keep work areas uncluttered, and clean frequently. Put unneeded materials back in storage promptly. Keep aisles, doors, and access to emergency equipment unobstructed at all times.
  • Keep barriers in place (shields, hood doors, lab doors).
  • Wear proper clothing and personal protective equipment.
  • Avoid working alone.
  • Store solvents properly in approved flammable liquid storage cabinets.
  • Limit open flames use to under fume hoods and only when constantly attended.
  • Keep combustibles away from open flames.
  • Do not heat solvents using hot plates.

Make sure workers are trained in the following emergency procedures:

  • Know what to do. You tend to do under stress what you have practiced or pre-planned. Therefore, planning, practice and drills are essential.
  • Know where things are, including the nearest fire extinguisher, fire alarm box, exit(s), telephone, emergency shower/eyewash, and first-aid kit, etc.
  • Be aware that emergencies are rarely "clean" and will often involve more than one type of problem. For example, an explosion may generate medical, fire, and contamination emergencies simultaneously.
  • Train workers and exercise the emergency plan.

For more information on laboratory fire safety see OSHAcademy Course 718, Fire Prevention Plans.

8. Each of the following is a best practice to help prevent laboratory fires EXCEPT _____.

a. avoiding working alone
b. heating solvents on hot plates
c. keeping combustibles away from open flames
d. storing solvents in approved storage cabinets

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Slips, Trips and Falls

Slips, Trips and Falls

Worker exposure to wet floors or spills and clutter can lead to slips/trips/falls and other possible injuries. In order to keep workers safe, employers should refer to:

General best practices to prevent slips, trips, and falls include:

  • Keep floors clean and dry. In addition to being a slip hazard, continually wet surfaces promote the growth of mold, fungi, and bacteria that can cause infections.
  • Provide warning (caution) signs for wet floor areas.
  • Where wet processes are used, maintain drainage and provide false floors, platforms, mats, or other dry standing places where practicable, or provide appropriate waterproof foot-gear.
  • The Walking/Working Surfaces Standard requires that all employers keep all places of employment clean and orderly and in a sanitary condition.
  • Keep aisles and passageways clear and in good repair, with no obstruction across or in aisles that could create a hazard.
  • Provide floor plugs for equipment, so that power cords need not run across pathways.
  • Keep exits free from obstruction. Access to exits must remain clear of obstructions at all times.
  • Ensure spills are reported and cleaned up immediately.
  • Eliminate cluttered or obstructed work areas.
  • Use prudent housekeeping procedures such as using caution signs, cleaning only one side of a passageway at a time, and provide good lighting for all halls and stairwells to help reduce accidents, especially during the night hours.
  • Instruct workers to use the handrail on stairs, to avoid undue speed, and to maintain an unobstructed view of the stairs ahead of them even if that means requesting help to manage a bulky load.
  • Eliminate uneven floor surfaces.
  • Promote safe work practices, even in cramped working spaces.
  • Avoid awkward positions, and use equipment that makes lifting easier.

9. Provide False floors, platforms, mats, or other dry standing places where practicable to help prevent _____.

a. slips, trips, and falls
b. stress from continued standing
c. strains to the back while lifting
d. falls from elevation

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Final Exam
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