Respiratory protective devices for use against chemical, biological, radiological and nuclear (CBRN) agents. Negative pressure, air purifying devices with full face mask. Specification|Chemical hazards, Safety devices, Supplied air breathing apparatus, Emergency equipment, Decontamination, Classification systems, Leak tests, Performance, Marking, Emergency services, Biological hazards, Designations, Gas-resistance tests, Flammability, Firefighting, Radiation hazards, Respirators, Chemical-resistance tests, Nuclear radiation, Breathing apparatus