General Laboratory Ventilation

Laboratory ventilation involves the use of supply and exhaust ventilation to control lab emissions, potential exposures, and chemical and biological hazards. A general lab ventilation system is designed to to the following:

  • dilute and remove contaminants through general exhaust;
  • provide make-up or replacement air, provide heating, cooling, and humidification; and
  • provide local exhaust for specific lab activities. 


General ventilation does not eliminate a potential exposure; local exhaust is the preferred method.

Ventilation Guidelines

Climate Controlled Spaces

Chemical Fume Hoods

Biosafety Cabinets

Local Exhaust and Containment Devices

Keep the lab door CLOSED.

General Ventilation: Typical Research Laboratory

Current ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) standards recommend that there be 6-10 air changes per hour. In animal care holding areas, the National Research Council's "Guide for the Care and Use of Laboratory Animals" recommends 12-15 air changes per hour.

Supply air introduced into the lab is provided by bringing 100% fresh outdoor air in. General lab ventilation dilutes contaminants and local exhaust (fume hoods) remove the contaminants. The picture below depicts how general lab ventilation works.


Negative Pressure

 Lab air is designed to be slightly under negative pressure to the hallway so that odors do not escape from the lab into the hallways. To maintain the negative pressure, lab doors should remain closed.

Fume hood sashes should also be lowered when not in use.

Climate Controlled Spaces

Climate controlled spaces such as warm rooms and cold rooms usually do not have fresh air provided to them. Do not work or store hazardous materials in these spaces that could cause harmful vapors to build up. Liquid nitrogen tanks CANNOT be stored in these spaces due to the displacement of oxygen. When working in a climate controlled space, be aware of reactions or processes that may cause off-gassing of harmful vapors. These processes should be completed in a fume hood.

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