Biosafety Levels

Published February 2000

Designations for laboratory types based on NIH guidelines. Each designation specifies laboratory practices, control of access, containment and special laboratory design. Also known as BSL 1-4.

BSL1: With respect to facilities design, a BSL1 lab has no particular facility standards other than those dictated by common decontamination and access control practices.
BSL2 requires that there be an autoclave for sterilization of wastes and contaminated materials in the same building.
BSL3 has special requirements for disposal of contaminated materials, lab access control, ventilation and air filtration, discharges, containment equipment, designs for easy and rapid decontamination and facility sealing.
BSL4 requirements (Formerly P1-P4) are similar to BSL3, but they are more stringent and the lab area itself must be constructed to form a sealed internal shell allowing vapor-phase decontamination.

To decontaminate filter housings and rooms in BSL4 areas, CDC uses an electrically operated portable paraformaldehyde generator that converts liquid formaldehyde to a gaseous vapor which is released into the containment area atmosphere. Surfaces are wiped free from any residual condensate after the required exposure time.

The big jump from BSL3 to BSL4 areas is the use of a space suit. Both areas use the same lab procedures, but in BSL4 areas, the workers have to wear the suit. A worker would never use a full body suit except when absolutely necessary because it makes work slower and requires more experience.