“Hazardous atmosphere” means an atmosphere that might expose employees to the risk of death, incapacitation, impairment of ability to self-rescue, injury, or acute illness from one or more of the following causes:

1. (a) Flammable gas, vapor, or mist in excess of 10 percent of its lower flammable limit (LFL);
2. (b) Airborne combustible dust at a concentration that meets or exceeds its LFL;
3. (c) Atmospheric oxygen concentration below 19.5 percent or above 23.5 percent; or
4. (d) Any other atmospheric condition that is immediately dangerous to life or health.

Source. #14431, eff 11-22-25, EXPIRES: 11-22-35