(NIOSH)/OSHA/EPA classification system is often used in describing general levels of protection:
OSHA requires Level A protection for workers in environments known to be immediately dangerous to life and health (i.e., where escape will be impaired or irreversible harm will occur within 30 minutes), and specifies Level B as the minimum protection for workers in danger of exposure to unknown chemical hazards. The NIOSH and the Mine Safety and Health Administration designate performance characteristics for respirators and provide approval for all commercially available respirators. Chemical protective clothing is not subject to performance standards established by a government agency, but the American Society for Testing and Materials (ASTM) has developed methods for testing the permeability of protective clothing materials against a battery of liquids and gases. The National Fire Protection Association (NFPA) has incorporated the ASTM test battery into the currently accepted standards for protective suits for hazardous chemical emergencies. Although a basic rule in selecting PPE is that the equipment be matched to the hazard, none of the ASTM permeability tests employ military nerve agents or vesicants. However, the NFPA is currently in the process of developing testing standards that will address the threat of nerve agents, cyanides, and vesicants.
In the event of a chemical-agent incident, it is most likely that the first emergency personnel on the scene will be police or firefighters. The former will almost never have chemical PPE and should simply relay observations to the latter. Firefighter ''turnout" or "bunker" gear designed for fire