Not a question we must know the answer to in order to be safe, but one that an old emergency responder ponders and now we know…
The National Institute of Occupational Safety and Health (NIOSH) defines an immediately dangerous to life or health condition as a situation
“that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment”
The IDLH limit represents the concentration of a chemical in the air to which healthy adult workers could be exposed (if their respirators fail) without suffering permanent or escape-impairing health effects. IDLH limits are derived by NIOSH based on animal and human data. Two factors are considered when establishing IDLH limits:
- Workers must be able to escape from the environment where they are exposed to hazardous chemicals without suffering
- permanent health damage or
- severe eye or respiratory tract irritation (or other conditions) that might impair their ability to escape.
NIOSH officially list 401 chemicals with an assigned IDLH level. You can also find IDLH values in CAMEO Chemicals or in the online version of the NIOSH Pocket Guide.