Selection Guide

The Center for Disease Control (CDC) in conjunction with the National Institutes of Health (NIH) has defined four biosafety levels, BSL-1 through BSL-4 (see: Biosafety in Microbiological and Biomedical Laboratories in reference materials). Within each level, laboratory practices and techniques, laboratory facilities and engineering controls have been recommended for the handling of hazards imposed by the infectious organisms within each biosafety level. The following is a summary of recommended biosafety levels for infectious agents.

I know my Bio-Safety Level.

  • BSL 1
  • BSL 2
  • BSL 3
  • BSL 4
BSL 1

Biosafety Level 1

Biosafety level 1 agents are not known to consistently cause disease in healthy adults.

Examples: Bacillus subtilis, Naegleria gruberi, canine hepatitis.

Safety Practices

Follow standard microbiological safety practices.

Expected Safety Equipment.

No safety equipment is required.

Laboratory Facility Requirements.

An open bench top and sink are required.

BSL 2

Biosafety Level 2

Biosafety level 2 agents are associated with human disease. Hazards are percutaneous injury, ingestion, mucous membrane exposure.

Examples: HIV, hepatitis B, salmonellae, toxoplasma.

Safety Practices

Follow biosafety level 1 practices, plus:

  • Limited Access.
  • Biohazard warning signs.
  • "Sharps" precautions.
  • Biosafety Manual for decontamination.

Expected Safety Equipment.

Use a physical containment device that is approved for all manipulations of agents that cause splashes or aerosols of infectious materials.

  • Class I Biosafety Cabinets
  • Class II biological safety cabinets

Primary barriers are Class I or Class II biological safety cabinets, or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials. Personnel protective equipment includes lab coats, gloves, and face protection as needed.

Laboratory Facility Requirements.

An open bench top, sink, and autoclave must be available.

BSL 3

Biosafety Level 3

Biosafety level 3 agents are indigenous or exotic agents with the potential for aerosol transmission. Disease may have serious or lethal consequences.

Examples: St Louis encephalitis virus, Coxiella burnetii, Mycobacterium tuberculosis.

Safety Practices

Follow biosafety level 2 practices, plus:

  • Controlled access.
  • Decontamination of all waste.
  • Decontamination of lab clothing before laundering.
  • Baseline serum.

Expected Safety Equipment.

Primary barriers are Class I or Class II biological safety cabinets or other physical containment devices, used for all open manipulations of agents. Personnel protective equipment (PPE) includes protective lab clothing, gloves, and respiratory protection as needed.

Laboratory Facility Requirements.

Follow Biosafety Level 2 precautions and:

  • Physical separation from access corridors.
  • Self-closing, double door access.
  • Exhaust air not re-circulated.
  • Negative pressure lab space.
BSL 4

Biosafety Level 4

Biosafety level 4 agents are dangerous/exotic agents which pose high risk of life-threatening disease, aerosol-transmitted lab infections or related agents with unknown risk of transmission.

Examples: Lassa fever virus, Marburg or Congo-Crimean hemorrhagic fever.

Safety Practices

Follow biosafety level 3 practices, plus:

  • Change clothing before entering.
  • Shower on exit.
  • All material decontaminated on exit from facility.

Expected Safety Equipment.

Primary barriers: All procedures are conducted in Class III biological safety glove boxes OR use a full-body, air-supplied, positive pressure personnel suit, in combination with Class I or Class II BSCs.

Laboratory Facility Requirements.

Follow Biosafety Level 3 precautions and:

  • Separate building or isolated zone.
  • Dedicated supply and exhaust, vacuum and decon systems.
  • Additional requirements as defined by safety documentation.

I know which microorganism
I am working with.

Find the appropriate Bio-safety level in your search results, and then refer to the Bio safety level tabs (at left) for more information. What number should I look for?

  • Bacteria
  • Viruses
  • Fungi
  • Parasites
Bacteria

Bacteria

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Viruses

Viruses

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Fungi

Fungi

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Parasites

Parasites

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