Laminar (unidirectional) airflow

Air moving in a single direction, usually vertically downward, at a uniform velocity across the working area, sweeping particles away from the critical zone. Unidirectional airflow is used in Grade A zones, LAF benches and biosafety cabinets. Annex 1 gives a guidance velocity of 0.36–0.54 m/s at the working position. Smoke studies show whether the flow stays unidirectional around equipment and during interventions.