NIOSH recently published final Immediately Dangerous to Life or Health (IDLH) Value Profiles for 14 chemicals: iron pentacarbonyl, acrylonitrile, 1,1-dichloro-1-fluoroethane (HCFC-141b), chloroacetyl chloride, chlorine pentafluoride, furan, hexafluoroacetone, n-butyl acrylate, benzontrile, methyl isocyanate, bromine pentafluoride, 1,3-butadiene, diketene, and butane. Each profile summarizes the health hazards of acute exposures to high airborne concentrations of a chemical and discusses the rationale for the chemical’s proposed IDLH value. According to NIOSH, an IDLH value, which is based on a 30-minute exposure duration, is the maximum level above which only a highly reliable breathing apparatus that provides “maximum worker protection” is permitted. provides links to each new document on NIOSH’s website. IDLH values are established to ensure workers’ ability to escape without loss of life or immediate or delayed irreversible health effects and to prevent severe eye or respiratory irritation or other reactions that would hinder escape.