Immediately Dangerous to Life and Health Values

Immediately Dangerous to Life or Health Concentrations (IDLH) are airborne concentrations that upon exposure are likely to result in death or immediate or delayed permanent adverse health effects, or prevent escape from the exposure environment. These values are frequently used in an occupational setting to define respiratory equipment requirements and in the evaluation of procedures for entering exposure environments. In a project sponsored by the National Institute for Occupational Safety and Health, TERA provided critical review and analysis of the human health and animal toxicity data upon which 15 of the IDLH concentrations were derived. The toxicity data were reviewed for each substance and an evaluation of the appropriateness of the existing IDLH value was made. A second level of the analysis included an evaluation of the consistency of the approach used in establishing the IDLH concentrations across a series of substances.


For more information, contact Mr. Andy Maier at 513-542-7475, extension 23 or