Understanding Biosafety Level Requirements for Laboratories: Lab Design, Procedures, and PPE

Research and biomedical labs often work with live and potentially dangerous microorganisms. For this reason, specific lab designs, lab safety procedures, and personal protective equipment for biosafety labs must be in place to prevent contamination or the accidental release of these contaminants.

In this article, we discuss the different Biological Safety Levels, the specific practices and regulations required at each level, and the type of biosafety PPE used in each laboratory setting.

What Are Biological Safety Levels (BSL)?

Biological Safety Levels (also called BSL or biosafety levels) are a series of clearly defined, closely regulated standards for laboratories throughout the world. These standards specifically apply to the lab design, lab safety procedures, and personal protective equipment (PPE) that must be used in biosafety labs.

As noted by the U.S. Department of Health and Human Services (HHS), the BSL classification system ensures that appropriate precautions are taken in order to protect workers, the public, and the environment from potentially harmful pathogens found in that setting.

Biosafety level requirements apply to a variety of industries, including biomedical research, pharmacological, ecological, environmental, and biological.

The 4 BSL Levels

There are four BSL levels or ranks, ranging from BSL-1 to BSL-4. A lab's BSL level is primarily based on the agents or organisms found within that particular lab. Additional factors that should be considered when determining lab levels include:

  • The severity of a potential infection or contamination by a given organism or agent
  • The origin of the organisms
  • Possible routes of exposure to the agents or organisms
  • Risks related to containment
  • The nature of the work being conducted by laboratory staff

Other types of labs, including those designated for animal research (ASBL) and agricultural research (BSL-Ag), have their own specific rules and regulations given the larger size of the organisms present in these facilities (e.g., animals, insects, and plants).

How BSL Levels Operate: Workplace Safety Practices, Job Functions, Facility Construction, and Access Restrictions based on Lab Levels

Biosafety levels dictate the type of work or research that can take place within a given lab, as well as the type of organisms that can be used or studied there. Biosafety levels even influence the overall design of the facility and the specialized safety equipment found inside.

It's important for anyone working within a biological laboratory setting to understand the four different biosafety level requirements, as well as the specific requirements for their laboratory, based on the lab's BSL rating. Let's take a closer look at the specific safety practices, typical activities or duties, and personnel access restrictions of each different biosafety level. (Personal protective equipment for biosafety labs is discussed in the following section.)


Laboratories designated as BSL-1, the lowest of the four biosafety levels, involve work with agents or organisms that pose a minimal threat to personnel and the environment.

Safety Practices

Only standard microbial practices are required at BSL-1 lab facilities, which include the following:

  • Work can be performed on a table or open lab bench
  • All spills should be immediately decontaminated
  • All sharps must be safely handled and disposed of
  • Infectious materials should be decontaminated prior to being disposed, typically with the use of an autoclave (autoclaves are machines that use superheated steam under pressure to kill microorganisms)
  • Activities must be performed in ways that minimize the risk of splashes and spills
  • People must practice basic hand hygiene, including before and after performing job functions and before leaving the laboratory
  • Eating, smoking, drinking, putting on cosmetics, and handling contact lenses or clear aligners is absolutely not permitted in the laboratory area
  • All pipetting must be done with mechanical pipette devices (no mouth pipetting)
  • Appropriate biohazard signage must be used

Common Pathogens Studied or Job Functions Performed

An example of an organism that could be studied in a BSL-1 lab would be the nonlethal agent E. coli.

Facility Construction

No special lab design features or equipment are required in BSL-1 labs. Laboratory surfaces, including benches, tables, and floors, should be easy to clean. Labs must also have sinks for handwashing. However, BSL-1 labs should have doors that separate the working laboratory space from the rest of the facility.

Access Restrictions

BSL-1 facilities are non-isolated. They do not have any special access restrictions, perhaps beyond general signage (e.g., "Authorized Personnel Only"), and do not have to be separate from other nearby facilities.

Understanding BSL-2

Laboratories designated as BSL-2 involve work with agents or organisms that are associated with human disease and pose moderate hazards to personnel and the environment.

Safety Practices

In addition to standard microbial practices, BSL-2 labs will also have additional safety practices in place:

  • Any procedure that can cause infection from aerosolized particles or splashes should be done inside a biological safety cabinet (BSC)
  • Autoclaves or other methods of decontamination must be made available for waste disposal

Common Pathogens Studied or Job Functions Performed

Organisms that might be studied in a BSL-2 lab include eastern equine encephalitis (EEE), human immunodeficiency virus (HIV), and Staphylococcus aureus.

Facility Construction

BSL-2 labs should have self-closing doors and have an eyewash station in addition to a sink for handwashing.

Access Restrictions

Outside personnel are often restricted access to BSL-2 labs when work is being conducted.


Laboratories designated as BSL-3 involve work with agents or organisms that are considered indigenous or exotic, agents that present a potential for aerosol transmission, and agents that can cause serious or potentially fatal diseases.

Safety Practices

In addition to following standard microbial practices, people working in BSL-3 labs are medically supervised and may be required to receive immunizations for the organisms or pathogens they work with. All work with organisms must be done within a BSC and autoclaves are generally used.

Common Pathogens Studied or Job Functions Performed

Organisms that might be studied in a BSL-2 lab include yellow fever, West Nile virus (WNV), and tuberculosis (TB). These agents are generally under strict control and registration by governmental agencies.

Facility Construction

Special design considerations for BSL-3 labs include the following:

  • Eyewash stations and hands-free sinks must be available near the exits
  • Exhaust air cannot be recirculated
  • Labs must have sustained directional air flow, with air drawn in from clear areas and directed toward potentially contaminated areas
  • Labs must have two sets of self-closing and locking doors

Access Restrictions

BSL-3 labs have restricted and controlled access at all times.


Laboratories designated as BSL-4 have the most stringent level of protection because they involve work with dangerous and exotic agents that pose a high risk of aerosol-transmitted infections and life-threatening illnesses. There are currently only 13 BSL-4 labs (planned or in operation) in the United States, and only 59 BSL-4 labs in the entire world.

Safety Practices

Labs designated with BSL-4 must fulfill all BSL-3 considerations, and must also have daily facility and equipment inspections as well as class III biological safety cabinets for all work involving organisms.

Personnel must be closely monitored for signs and symptoms of illness. Logs must be kept of the dates and times of all personnel, equipment, and supplies entering and leaving containment areas. All materials leaving the lab space must be thoroughly decontaminated.

Finally, laboratory personnel must change their clothes prior to entering the lab and must shower prior to exiting the lab space.

Common Pathogens Studied or Job Functions Performed

Organisms that might be studied in a BSL-4 lab include Ebola virus and Marburg virus. BSL-4 labs are often the setting of riskier activities, including gain of function (GOF) research. GOF research is a type of medical research used to genetically modify a microorganism, typically to make the microorganism more transmissible, virulent, or immunogenic (able to provoke an immune response in a human or animal).

BSL-3 labs are also permitted to perform GOF research.

Facility Construction

BSL-4 labs are typically found in separate buildings or in strictly isolated areas of a building. The lab itself must have dedicated exhaust air, vacuum lines, and decontamination systems.

Access Restrictions

BSL-4 labs are heavily restricted and are often completely isolated from nearby buildings or facilities, in addition to being closed off to any outside personnel.

Biosafety PPE for Biosafety Labs: Using the Right Personal Protective Equipment for The Right Lab Level

Personal protective equipment is required for use in all BSL facilities. However, the specific type of PPE required will vary depending on the biosafety level and activities performed.

Personal protective equipment for biosafety labs can be categorized as follows:

  • BSL-1: lab coats, gloves, and eye protection should be worn as needed
  • BSL-2: lab coats, gloves, eye protection, and face shields
  • BSL-3: lab coats, gloves, eye protection, face shields, and possibly respirators
  • BSL-4: personnel in this setting must wear full body, air-supplied, positive pressure suits


Biosafety levels are used to classify laboratories based on the type of organisms and nature of work found within, for the express purpose of keeping personnel, the public, and the environment safe. To learn how disposable personal protective equipment can help your laboratory remain in compliance, contact International Enviroguard today at 1-866-734-7515.