Horizontal laminar flow hoods pull air from the environment; the air goes through a filter and then blows smoothly out the front of the hood back into the room. A vertical laminar flow hood works in mostly the same way, but the air is blown from the top of the hood straight down.

Vertical vs Horizontal: Making the Choice They are most useful when limiting contamination is your main priority. On the other hand, a vertical laminar flow hood is preferable if there is any concern about the safety of the user being exposed to the samples.

The worker will be exposed to the materials being manipulated on the clean bench potentially resulting in hypersensitivity, toxicity or infection depending on the materials being handled. Horizontal airflow “clean benches” must never be used as a substitute for a biological safety cabinet.

The Right Way to Clean: Clean the back wall (of a vertical laminar flow hood) next, going from top to bottom. Clean the sides (swiping from top to bottom in overlapping lines). The work surface should be the last surface cleaned, beginning in the back and ending at the front of the unit.