IDLH 04
IDLH 04 : Immediately Dangerous to Life and Health (IDLH) is a reference threshold defined by the U.S. National Institute for Occupational Safety and Health (NIOSH). Concentrations below IDLH shall allow unprotected exposure up to 30 minutes without suffering severe health effects. Other than for ERPG or AEGL thresholds, no severity levels are defined