The Occupational Safety and Health Administration (OSHA) regulation (1910.134(b)) defines the term as "an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape from a dangerous atmosphere."
Det udregnes ved hjælp af LD50 eller LC50.Occupational Safety and Health Administration (OSHA)-reguleringen (1910.134(b)) definerer begrebet som "en atmosfære der udgør en umiddelbar trussel mod liv, ville forårsage irreversible ugunstige sundhedsvirkninger, eller ville hæmme et individs evne til at undslippe fra en farlig atmosfære."