Hazardous atmosphere
An atmosphere that may expose employees to the risk of death, incapacitation, impairment of ability to self-rescue (that is, escape unaided from a permit space), injury, or acute illness from one or more of the following causes:1. Flammable gas, vapor, or mist in excess of 10 percent of its lower flammable limit (LFL);2. Airborne combustible dust at a concentration that meets or exceeds its LFL;3. NOTE: This concentration may be approximated as a condition in which the dust obscures vision at a distance of 5 feet (1.52 m) or less.4. Atmospheric oxygen concentration below 19.5 percent or above 23.5 percent;5. Atmospheric concentration of any substance for which a dose or a permissible exposure limit is published in Subpart G, Occupational Health and Environmental Control, or in Subpart Z, Toxic and Hazardous Substances, of this Part and which could result in employee exposure in excess of its dose or permissible exposure limit; 6. Any other atmospheric condition that is immediately dangerous to life or health.
