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Controlling Laboratory Hazards

Hierarchy of Controls
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The Hierarchy of Controls

There are many different types of hazards in the lab. Hazards are generally categorized into two types: 1) hazardous conditions and 2) unsafe work practices/behaviors.

  • Hazardous conditions include unsafe materials, equipment, environment and employees.
  • Unsafe work practices and behaviors include allowing untrained workers to perform hazardous tasks, taking unsafe shortcuts, horseplay, or long work schedules.

To combat these hazardous conditions and unsafe work practices, control strategies, called the "Hierarchy of Controls," have been developed. Traditionally, a hierarchy of strategies to control hazards has been used to implement feasible and effective controls. In our training, we encourage the use of the "Hierarchy of Controls" (HOC) described in ANSI/ASSP Z10-2012, Occupational Health and Safety Management Systems.

The hierarchy of controls prioritizes intervention strategies based on the premise that the best way to control a hazard is to systematically remove it from the workplace, rather than relying on workers to reduce their exposure. The types of measures that may be used to protect laboratory workers, prioritized from the most effective to least effective, are:

Hazard Controls

  1. Elimination
  2. Substitution
  3. Engineering controls

Exposure Controls

  1. Warnings
  2. Administrative controls
  3. Personal protective equipment

Following the hierarchy normally leads to the implementation of inherently safer systems, ones where the risk of illness or injury have been substantially reduced. Let's take a closer look at the hierarchy of control strategies.

1. To combat hazardous conditions and unsafe work practices in the laboratory, control strategies, called _____ have been developed.

a. engineering controls
b. administrative control
c. substitution
d. the Hierarchy of Controls

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Elimination and Substitution

Eliminate the Hazard – Napo

Simply stated, elimination removes a hazard, and substitution replaces a hazard.

These strategies are considered first because they are most effective in completely eliminating the hazard. Removing or replacing equipment or machinery may be expensive, but remember, according to the National Safety Council, the total economic cost of a work-related medically-consulted injury is over $41,000, and $1,200,000 per death.

Elimination and substitution, while most effective at reducing hazards, tend to be the most difficult to implement in an existing process. If the process is still at the design or development stage, the elimination and substitution of hazards may be inexpensive and simple to implement. However, for an existing process, major changes in equipment and procedures may be quite expensive.

Some examples of these two strategies include:

  • Removing the source of excessive temperatures, noise, or pressure
  • Substituting a toxic chemical with a less toxic or non-toxic chemical

2. Elimination, as a hazard control strategy, is considered the top priority because _____.

a. it replaces the hazard
b. it removes the hazard
c. it replaces exposure
d. it removes the exposure

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Engineering Controls

This HVAC unit is engineered to prevent exposure to moving parts.

Engineering controls work through the design or redesign of tools, equipment, and machinery to remove the hazard at the source. If elimination or substitution is not possible, OSHA law requires employers to attempt to remove hazards through the use of feasible engineering controls because they also have the potential to eliminate or reduce exposure to hazards in the lab.

These controls focus on eliminating or reducing the hazard at the source of the hazard, during the process, or and at the worker. The basic concept behind engineering controls is that, to the extent feasible, the work environment and the job itself should be designed to eliminate hazards or reduce exposure using three primary methods:

  1. Enclosure. Methods to completely isolate the source of the hazard from employees.
  2. Barriers. If complete enclosure does not adequate protect employees, barriers may be installed to keep employees away from the source of exposure.
  3. Ventilation. Local exhaust ventilation removes or dilutes air contaminants to reduce exposure to acceptable levels.
  4. Design. Designing tools and equipment to make sure they are safe and meet the needs of the worker.

3. If elimination or substitution is not possible, employers should attempt to remove hazards through the use of _____.

a. administrative controls
b. engineering controls
c. personal protective equipment
d. warnings

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Glove box station
This glove box station protects by completely enclosing the hazard.

When you cannot remove a hazard and cannot replace it with a less hazardous alternative, the next best control in the laboratory is enclosure. Properly enclosing a hazard means that there is no hazard exposure to workers during normal operations. There still will be potential exposure to workers during maintenance operations or if the enclosure system breaks down. For those situations, additional controls such as safe work practices or personal protective equipment (PPE) may be necessary to control exposure.

Some examples of effective enclosure designs are:

  • Complete enclosure of moving parts of machinery;
  • Complete containment of toxic liquids or gases from the beginning to end of a process;
  • Glove box operations to enclose work with dangerous microorganisms, radioisotopes, or toxic substances; and
  • Complete containment of noise, heat, or pressure producing processes with materials especially designed for those purposes.

4. During normal operations, there is no exposure to hazards by _____.

a. efficient work procedures
b. the proper enclosure of hazards
c. warning signs and alarms
d. a lockout/tagout condition

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Glove box station
Partial enclosure, a barrier, and ventilation is used to reduce exposure to air contaminants.

When the hazard cannot be removed, replaced, or completely enclosed, the next best approach is to place a barrier or guard between the worker and the hazard to prevent exposure. For more information on effective barriers, see OSHAcademy Course 726, Introduction to Machine Guarding.

Examples of effective barriers include:

  • Machine guarding to separate the hazard from the employee
  • Baffles used as noise-absorbing barriers
  • Nuclear radiation or heat shields


Ventilation involves removing potential air contaminants during normal operations. Consequently, it should be used only in conjunction with other types of controls, such as safe work practices designed specifically for the site condition and/or PPE. In the laboratory, the most common type of ventilation is local exhaust ventilation. Some examples of ventilation controls include:

  • Local exhaust ventilation. The friction between the wheel of a disc sander/belt of the belt sander and the ceramic workpiece results in the release of particles and fibers. Local exhaust ventilation is designed to capture the contaminant near the point of release. The effectiveness of a local exhaust ventilation system is highly dependent on the proximity of the exhaust hood to the point of emission.
  • Mine assay laboratories. Mine assay laboratories employ local exhaust ventilation and partial enclosures in the sample preparation area, flux mixing, and fire assay areas.
  • Cryosurgical units. Airborne concentrations of nitrous oxide (N2O) from cryosurgical units can be effectively controlled by ventilation and equipment maintenance, and if this is not possible, through substitution with a less hazardous cryogenic gas. Most modern N2O cryosurgical units are equipped with a scavenging port where the gas is exhausted.
  • Portable air cleaners (PACs). Indoor air contains suspended biological particulate matter (bioaerosols) that can pose a threat to public health through infectious diseases. PACs remove or inactivate bioaerosols in the workplace through the use of air cleaning mechanisms including a high-efficiency particulate air (HEPA) filters, electrostatic precipitators, enhanced filters, and an ozone/ion generators.

5. In the laboratory, the most common type of ventilation is _____.

a. individual ventilation
b. local exhaust ventilation
c. forced-air ventilation
d. natural ventilation

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Design Controls

Glove box station
Proper design helps eliminate exposure.

Last, but not least, the design or redesign of tools, equipment, and machinery is important because it can eliminate or reduce a hazard at the source. Some examples of design methods include:

  • Noise. Engineering controls are defined as any modification or replacement of equipment, or related physical change at the noise source or along the transmission path (with the exception of PPE hearing protection devices), that reduces the noise level at the worker's ear. Methods include reducing vibration and mechanical impact noise, proper lubrication, alignment of moving parts, mufflers and silencers, and reducing the speed of equipment.
  • Medical and Laboratory equipment. Examples include chemical fume hoods, air handlers, sharps disposal containers, self-sheathing needles, safer medical devices, such as sharps with engineered sharps injury protections and needleless systems that isolate or remove pathogen hazards from the workplace.
  • Electric tools. Rotary/orbital and straight line/reciprocating sanders, equipped with high-velocity, low-volume (HVLV) local exhaust ventilation as part of the tool's design, are recommended because they have been shown to be effective in reducing total dust concentrations during the sanding of body filling compounds.
  • Work Station Design. Much of the equipment used in some industries is nonadjustable. Redesigning workstations will eliminate the need for excessive reaching and many awkward postures. Some dry cleaning equipment manufacturers are beginning to market adjustable height workstations.

Visit the NIOSH Engineering Controls Database for more examples of engineering controls in laboratories and other workplaces.

6. Design controls eliminate or reduce _____.

a. exposure through effective procedures
b. hazards at the source
c. exposure with personal protective equipment
d. exposure in the environment

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Safe Chemical Handling


Warnings may be visual, audible, or both. They may also be tactile.

  • Visual warnings you can see - include signs, labels, tags, and lights.
  • Audible warnings you can hear -include alarms, bells, beepers, sirens, horns and announcement systems.
  • Tactile warnings you can feel - may include vibration devices or air fans.

Administrative Controls

Administrative controls include the development and deployment of safety policies, processes, procedures, rules, training, scheduling, and safe work practices. Ultimately, effective administrative controls will successfully control the human behaviors that result in most workplace accidents. Examples of laboratory administrative controls include:

  • Developing a Chemical Hygiene Plan, and
  • Developing Standard Operating Procedures for chemical handling.

Administrative controls are only as effective as the safety management system that supports them. It's always better to eliminate the hazard so that you don't have to rely on management controls that tend to work only as long as employees behave.

To make sure these controls are effective in the long term, they must be designed from a base of solid hazard analysis and sustained by a supportive safety culture. They then must be accompanied by adequate resources, training, supervision, and appropriate consequences. Remember, administrative controls should be used in conjunction with, and not as a substitute for engineering controls.

7. Hazard warnings include all of the following types EXCEPT _____.

a. spatial
b. visual
c. audible
d. tactile

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Personal Protective Equipment (PPE)

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Using personal protective equipment is a very important safe work practice. It's important to remember, like other administrative controls, the use of PPE does not control the hazard itself, but rather it merely controls exposure to the hazard by setting up a barrier between the employee and the hazard. Use of PPE may also be appropriate for controlling hazards while engineering controls are being installed or work practices developed.

PPE Drawbacks

The limitations and drawbacks of safe work practices also apply to PPE. Employees need training in why the PPE is necessary and how to use and maintain it. It also is important to understand that PPE is designed for specific functions and are not suitable in all situations. For example, no one type of glove or apron will protect against all solvents. To pick the appropriate glove or apron, you should refer to recommendations on the safety data sheets of the chemicals you are using.

Your employees need positive reinforcement and fair, consistent enforcement of the rules governing PPE use. Some employees may resist wearing PPE according to the rules, because some PPE is uncomfortable and puts additional stress on employees, making it unpleasant or difficult for them to work safely. This is a significant drawback, particularly where heat stress is already a factor in the work environment. An ill-fitting or improperly selected respirator is particularly hazardous, since respirators are used only where other feasible controls have failed to eliminate a hazard.

8. To pick the appropriate glove or apron, you should refer to recommendations on the _____.

a. PPE label
b. chemical label
c. safety data sheets
d. manufacturer's brochure

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Interim Measures

When a hazard is recognized, the preferred correction or control cannot always be accomplished immediately. However, in virtually all situations, interim measures can be taken to eliminate or reduce worker risk. These can range from taping down wires that pose a tripping hazard to actually shutting down an operation temporarily.

The importance of taking these interim protective actions cannot be overemphasized. There is no way to predict when a hazard will cause serious harm, and no justification to continue exposing workers unnecessarily to risk. By the way, OSHA believes there is always some kind of interim measure that can be used to temporarily reduce or remove a hazard.


Maintenance Strategies to Control Hazards

What two general types of maintenance processes are needed?

  • Preventive maintenance to make sure equipment and machinery operates safely and smoothly
  • Corrective maintenance to make sure equipment and machinery gets back into safe operation quickly

Final Thoughts

The hierarchy of controls is the standard system of strategies to effectively eliminate workplace hazards. Remember, the first question to ask when considering ways to control the hazards in your laboratory is, "can we eliminate, replace, or use engineering controls?" You will more than likely use a combination of strategies to control hazards. Whatever it takes, do it. You are not just saving a life: you are saving someone's father, mother, son, or a daughter. It's worth the effort.

9. What does OSHA believe about how often an employer can use some kind of interim measure that can temporarily reduce or remove a hazard?

a. They hardly ever work to reduce hazards
b. They work sometimes, but not all the time
c. You can usually rely on a temporary measure
d. There is always a temporary measure

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