Think of a control measure as an action aimed to eliminate a hazard completely. If the hazard you've identified can't be eliminated, follow the hierarchy of controls to select the next-best control to mitigate the risk of an accident, incident, injury, or near-miss in the laboratory.

Your risk assessment may reveal that you will need a temporary control measure until you can put a better and more permanent control in place.  

Selecting your controls is a key part of the process of identifying and evaluating hazards in your lab. According to the Canadian Centre for Occupational Health and Safety Fact Sheet, controls are usually placed:

  • At the source (where the hazard comes from)
  • Along the path (where the hazard travels)
  • With/on the worker

There are several types of control measures that fall into three main categories (in order of priority and effectiveness):

  1. Elimination
  2. Engineering
  3. Administrative
  4. Personal Protective Equipment

The Hierarchy of Controls

The National Institute for Occupational Safety and Health (NIOSH) depicts the hierarchy of controls as an inverted pyramid with the most effective types of control measure (elimination) at the top and the least effective (personal protective equipment) at the bottom.

Hierarchy of Controsl
Source: http://www.cdc.gov/niosh/topics/hierarchy

Elimination and Substitution

Elimination and substitution are considered the most effective control measures. They are easiest to achieve for brand new processes. They can be more difficult to implement for existing processes, because new and/or more expensive equipment and materials may be required.


Completely get rid of chemicals, materials, processes, and equipment that are unnecessary to your specific experiment.

Check if your equipment is well-worn, check dates, and refer to manufacturer's recommendations.


Switch out processes, equipment, material, or other components, where applicable.

Think about the amount of chemicals or potentially hazardous materials you are using. Can you reduce the amount and still achieve the desired result?

Engineering Controls

Although elimination and substitution are separate controls in the hierarchy of control measures, they are also considered engineering controls because they are designed to remove the hazardous source before the worker makes contact. Other forms of engineering controls include:  

  • Isolation
    Reduce or remove hazards by separation in time or space. (May be particularly helpful in a shared lab space where different types of chemicals are being used.)
  • Enclosure
    Place the material or process in a closed system.
  • Transportation
    Move hazardous materials where fewer workers are present.
  • Guarding and shielding
    Install guards to provide protection from moving parts or electrical connections.
    Shielding provides protection from potential explosions
  • Ventilation
    Use fume hoods, fans, air ducts and air filters.

Administrative Controls

While engineering controls seek to eliminate hazards, administrative controls aim to minimize a lab worker's exposure. Administrative controls are the existing safety rules and protocols put in place for workers in the lab to follow. Following are examples of administrative controls:

Personal Protective Equipment (PPE)

Even though the hierarchy of control measures indicates PPE is the least effective of control measure, it should absolutely be used, in case other control measures fail. The success of PPE depends in part on whether or not lab workers actually use it.

Eye goggles, hearing protection, and protective clothing (e.g., lab coats and gloves) are the most recognizable and most used PPE in the lab.

PPE is always essential, and especially critical in the following circumstances:

  • When engineering controls are not feasible or they do not totally eliminate a hazard;
  • As a temporary control while engineering controls are being developed;
  • In emergency situations.

Real World Example: Benzene as a Solvent

Using benzene as a solvent in a process introduces a physical (fire) and a health (cancer) hazard. If substitution with a less hazardous solvent is not possible, then there should be controls in place for the associated flammability and health risks. Control measures would consist of:

  • Removing ignition sources (Engineering)
  • Having an absorbent on hand for spills
  • Referring to the lab SOP for using benzene prior to working with the chemical (Administrative)

This collection of methods and tools for assessing hazards in research laboratories is based on the publication, Identifying and Evaluating Hazards in Research Laboratories [PDF]. The guide was published in 2015 by the Hazard Identification and Evaluation Task Force of the American Chemical Society’s Committee on Chemical Safety in response to a recommendation from the U.S. Chemical Safety Board.

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