<P> A laminar flow cabinet or laminar flow closet or tissue culture hood is a carefully enclosed bench designed to prevent contamination of semiconductor wafers, biological samples, or any particle sensitive materials . Air is drawn through a HEPA filter and blown in a very smooth, laminar flow towards the user . Due to the direction of air flow, the sample is protected from the user but the user is not protected from the sample . The cabinet is usually made of stainless steel with no gaps or joints where spores might collect . </P> <P> Such hoods exist in both horizontal and vertical configurations, and there are many different types of cabinets with a variety of airflow patterns and acceptable uses . </P> <P> Laminar flow cabinets may have a UV - C germicidal lamp to sterilize the interior and contents before usage to prevent contamination of experiment . Germicidal lamps are usually kept on for 15 minutes to sterilize the interior and no contact is to be made with a laminar flow hood during this time . During this time, scientists normally prepare other materials to maximize efficiency . (It is important to switch this light off during use, to limit exposure to skin and eyes as stray ultraviolet light emissions can cause cancer and cataracts .) </P>

How does a laminar hood air flow work