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Immediately Dangerous To Life or Health (IDLH) Values

Historical Documentation


The immediately dangerous to life or health (IDLH) values used by the National Institute for Occupational Safety and Health (NIOSH) as respirator selection criteria were first developed in the mid-1970’s. The original IDLH values were developed as part of a joint effort by OSHA and NIOSH called the Standard Completion Program (SCP). The goal of the SCP was to develop substance-specific draft standards with supporting documentation that contained technical information and recommendations needed for the promulgation of new occupational health regulations, such as the IDLH values. The Documentation for Immediately Dangerous to Life or Health (IDLH) Concentrations is a compilation of the rationale and sources of information used by NIOSH during the original determination of 387 SCP IDLH values.