After identifying the hazards in your lab, the next steps are to properly evaluate and control the hazards. These steps may be very specific to your lab, so be sure to take your time and ask for help when needed. Also, be sure to check if your lab building has specific emergency safety features


Evaluating risks is a key step in working with hazardous materials, instrumentation, and equipment. A risk assessment will in part examine the probability that an adverse event will occur and the consequence of that event when working with hazardous materials. Ultimately, this can help to determine the proper controls that will be needed to avoid the adverse event. A risk assessment can reduce the likelihood that faculty, staff, or students may be unnecessarily exposed to a laboratory hazard.

Risk Assessment

Supervisors are responsible for properly assessing the hazards in their individual lab areas. Safety staff are available to assist with conducting these assessments.

An exposure assessment is one portion of a risk assessment. This portion examines the exposure limits of hazardous chemicals in order to help determine appropriate controls. There are a variety of exposure limits that different regulatory agencies use that may be useful. Every worker should be exposed to levels below these limits when working with chemicals. 

  • PEL, Permissible Exposure Limit - OSHA
  • TLV, Threshold Limit Value - ACGIH
  • REL, Recommended Exposure Limit - NIOSH

Exposure assessments can be performed in two ways: monitoring and professional opinion. 

A proper risk assessment includes the following:

  • Perform a comprehensive review of a specific hazard (including an exposure assessment), e.g. chemical or biological material to be used or hazardous activity or procedure to be performed,
  • Document the review (see below),
  • Submit specific protocols to appropriate UVM review boards as needed (IBC, IRB, IACUC, etc.), and
  • Re-evaluate lab tasks when changes are made to current procedures. 

Contact Safety staff if you would like us to help conduct a comprehensive review of your lab materials or activities. Always be sure to have proper controls in place before performing a lab experiment or procedure.


Whenever a risk assessment is completed, it must also be documented. Two options are Chemical Use Planning Forms (CUPFs), Standard Operating Procedures (SOPs). CUPFs can be used for specific chemicals or groups of chemicals that have the same hazards and will be used in the same way with the same controls. SOPs are the most specific way to document safe use and include step-by-step procedural details.



After lab hazards have been identified and evalutated, all must be controlled to avoid exposure. Traditionally, a hierarchy of controls is used to determine how to implement feasible and effective controls for any hazard. Control methods at the top of the hierarchy are potentially more effective and protective than those at the bottom. This is why it is important to always follow the order when considering how to control any and all laboratory hazards. Following the hierarchy can lead to the implementation of inherently safer systems, where the risk of illness or injury can be substantially reduced. The sections below describe the individual portions of the hierarchy in order: elimination, substitution, engineering controls, work practices, and personal protective equipment.


Can you eliminate the hazard? Eliminating the hazard means physically removing the hazard from the procedure or the work area. Eliminating the hazard is the most effective method of minimizing an exposure to any hazard.  However, elimination is not often a viable option.


  • Dispose of an old hazardous chemical
  • Remove an extension cord from laying across a traveled path
  • Lock and Tag a dangerous machine out of service


Substitution replaces a hazard with an action or material that is less hazardous.

Examples: Replace ethidium bromide, a mutagen, with GelRed, SafeRed, or SYBR Safe.

However, be wary of marketing terms such as "natural", "green", etc.  Carefully review the Safety Data Sheet of any replacement product. Contact Safety staff if you are unsure if the replacement is actually a better choice.

Note: Though the substitution may be less hazardous, do NOT dispose of these less hazardous ethidium bromide replacements in the UVM trash. Label and collect them for proper lab waste disposal.

Engineering Controls

Engineering controls are used to remove a hazard or place a barrier between the user and the hazard. Engineering controls may be ducted and exhausted out of the building or may use a filter to capture aerosols, particles, etc. Well-designed engineering controls can provide highly effective protection to the user.

Examples of primary engineering controls used in laboratories include the following:

The initial cost of an engineering control can often be higher than the cost of administrative controls or personal protective equipment. However, over the long term, operating costs are frequently lower. Engineering controls often require some form of maintenance such as calibration of monitors and alarms, filter replacement, and/or specific airflow certifications upon installation or annually.

Visit the general laboratory ventilation webpage, or task-oriented ventilation webpage, for more information. Your building may already have specific features designed to control hazards, find these at the Building-specific Safety Features webpage.

If you need/want to add an engineering control that affects part of any UVM building system (HVAC, electrical, plumbing), the control must be installed by UVM Facilities, Design, and Construction (FD&C) services group or UVM's Physical Plant Department (PPD).

Work Practices

Work practices, or "administrative controls," include altering the way in which a procedure is done, monitored, and/or restricted.


  • Using proper labeling and signage to communicate the hazard to others
  • Conducting monthly lab self-inspections to regularly eliminate any noticeable hazards
  • Instituting a "buddy system" when hazardous work is being performed
  • Having an emergency plan: considering the "What if...." then train lab users before an emergency happens
  • Relocating a piece of equipment so the flow of work can be done safely and more efficiently
  • Restricting the length of time that a person is exposed to noise, a particular substance, or a specific activity
  • Enforcing rules about daily housekeeping
  • Performing regular equipment maintenance
  • Following the Working Alone Procedures (PDF)
  • Following Unattended Operations Procedures (PDF)
  • Creating a written Standard Operating Procedure (SOP)

For more information on writing an SOP for your lab and to view some guidelines for specific chemical hazards, visit the Specific Hazard webpage.

As you can see, administrative controls are a crucial part of controlling any hazard. 

Personal Protective Equipment

Personal protective equipment (PPE) is often referred to as the last line of defense.  As a control method, PPE has  proven to be less effective than other control measures, which is why it is generally used with some form of engineering and/or administrative control.

Proper PPE must be made available for an emergency response or cleanup procedure as well. Proper PPE increases the level of safety protection from a chemical, biological, or physical hazard during an unexpected event.

More information about personal protective equipment is available.