There is a class of lab hood called biologic safety hood. From what I can see they appear to have a negative pressure in order to prevent the exit of harmful vapors or biologic agents but I wonder if they are filtered like a laminar flow or clean room hood.
That is, what would one use to provide negative pressure, like with a fume hood and yet prevent contamination of a biologic or other sensitive media with microparticulalate contaminants.
A fume hood sucks dirty air from the front preventing user exposure from harmful air born substances within the hood. But it would contaminate, for example, a biologic culture medium with room air as well as draw air across the operators hands and arms - another potential source of contaminant.
A laminar flow hood OTOH provides clean room air from the proper direction from specimen to user, thus preventing contamination but it does blow out onto the user, exposing him to airborne pathogens from the specimen.
It looks to me like the biologic safety hood provides a negative air flow from the front but I am not sure if there is filtered, laminar flow within. There could be but I can’t find any documentation of exactly how these things work or any specs.
