Make sure the activity is appropriate for a laminar flow hood and not a Biological Safety Cabinet.

The former blows HEPA filter air out of the cabinet into the face of the user. It is designed to keep the activity sterile but NOT protect the user. They are used in biology primarily for pouring sterile petriplates, culturing of non-pathogenic and non-allergenic cultures, etc. They also get used in electronics and other industries in clean rooms.

If they are working on pathogenic cultures, or need to protect the user from the work they are doing, then you need a biological safety cabinet (BSC). They provide HEPA filtered air to keep the cultures from getting contaminated as well as HEPA filtered exhaust air. BSC's can exhaust into the room (cheaper) or into dedicated ductwork.

Laminar flow hoods should be clearly labeled to not be used for pathogenic work.

Note that many laminar flow (as well as BSC's) often use UV lights to sterilize the surface of the units. Putting the discussion of the effectiveness of this sterilization procedure aside, since most laminar hoods do not have a sash, they need other protective measures to prevent UV exposure to the worker. In BSC's, a secondary protection is to put a sash height detector to kill the UV light if it gets opened before the light is turned off.

Finally, BSC's should be calibrated and checked by a certified professional and should be re-certified annually.

Jeff Lewin

Biological Sciences

Michigan Technological University