ABSTRACT
Hazards identified during the hazard assessment and risk analysis phase of an incident, typical the basis for choosing the appropriate standard and its associated protective equipment. An unknown environment represents a situation during the initial parts of a response with the identity of the agent or threat that has not yet been identified, and the atmosphere is suspect to be at or above the Immediately Dangerous to Life and Health (IDLH). An unknown environment can encompass any weapons of mass destruction (WMD) chemical biological agent or toxic industrial chemical but would not take into account the potential for high-energy penetrating radiological hazards, thermal hazards, or explosive hazards. The National Institute for Occupational Safety and Health (NIOSH), the governing organization of OSHA, has embarked upon a program to develop and establish testing criteria and certification standards for breathing systems specifically to WMD chemical, biological, radiological and nuclear (CBRN) substances.
