This British Standard specifies requirements for negative pressure air purifying devices (APDs) with full face mask intended to be used during rescue, evacuation, escape, hazard containment and decontamination, and similar activities by emergency responders (fire, ambulance, police, and associated civilian agencies and workers) in areas contaminated by chemical, biological, radiological and nuclear (CBRN) agents.

This British Standard contains the requirements for designation, classification, testing and marking of the device.