NIOSH intends to develop new or updated Immediately Dangerous to Life or Health values for six chemicals: allyl alcohol, bromine chloride, hydrogen bromide, hydrogen iodide, propylene imine, and lewisite, a chemical warfare agent. The agency’s IDLH values are established to ensure workers’ ability to escape from a contaminated environment in the event that their respiratory protection equipment fails. IDLH values are also intended to represent a maximum level above which workers should not be exposed without highly reliable respiratory protection. As part of the process for developing IDLH values, NIOSH will evaluate scientific data for the six chemicals. The agency asks stakeholders to submit published and unpublished reports and research findings to evaluate the possible acute health risks of occupational exposure to the chemicals. Reports of acute animal toxicity studies, acute human toxicology studies, and mode of action studies are additional examples of the type of information NIOSH is requesting. Further details, including instructions for submitting information, are available in the Federal Register. NIOSH updated its method for determining IDLH values in 2013 via Current Intelligence Bulletin 66: Derivation of Immediately Dangerous to Life or Health (IDLH) Values, or CIB 66. The document notes that occupational health and safety professionals have incorporated IDLH values into risk management plans for operations in high-risk environments such as confined spaces, and in guidance for emergency responders. More information on IDLH values can be found on the NIOSH website.