Negative Pressurization

Airflow shall be from low-hazard to high-hazard areas.


Anterooms may be necessary for certain applications, such as clean rooms or tissue culture rooms. Potentially harmful aerosols can escape from the containment of the laboratory room unless the room air pressure to adjacent nonlaboratory areas is negative.


UC Practice

CDC-NIH Biosafety in Microbiological and Biomedical Laboratories

Prudent Practices in the Laboratory, Sections 8.C and 8.D

NFPA 45, 6.4.4


The laboratory airflow control system shall continuously determine supply airflow and exhaust airflow, and by comparing these values, shall ensure design lab pressurization is maintained. A room offset value of 10% of the maximum air value to the room is recommended, or 100 cfm, whichever is greater.


See the 'General Laboratory Ventilation Design Issues' section of this chapter, specifically point #1.


NFPA 45, 6–4.4


If laboratory pressurization becomes critical to prevent undesirable airflow from one area to another in high-hazardous applications, an airlock may be necessary. Consult EH&S for guidance.




A corridor shall not be used as a plenum.