NIOSH has published new immediately dangerous to life or health (IDLH) values for the chemicals , , and . IDLH values are established to ensure workers’ ability to escape from a contaminated environment if their respiratory protection equipment fails. IDLH values represent a maximum level above which workers should not be exposed without highly reliable respiratory protection. Each NIOSH “IDLH value profile” summarizes the health hazards of acute exposures to high airborne concentrations of a chemical and discusses the rationale for the chemical’s IDLH value. Bromine trifluoride (BrF3) and chlorine trifluoride are halogen fluorides. According to the National Research Council, BrF3 is used as a solvent for other fluorides and as an oxidizing agent in cutting tools. Ethylene bromide is used as a chemical intermediate in the synthesis of resins, waxes, dyes, and pharmaceuticals. NIOSH set the IDLH value for BrF3 at 12 ppm (67 mg/m3). Because data for BrF3 was inadequate, the agency used data from studies with chlorine trifluoride—a chemical with similar structure, reaction mechanisms, and potency—to develop the value for BrF3. The IDLH value for chlorine trifluoride is set at 12 ppm (45 mg/m3) and is based on data on eye irritation in rats exposed to the chemical at a concentration of 480 ppm for five minutes, which researchers determined to impair escape. The IDLH value for ethylene dibromide, 46 ppm (354 mg/m3), is based on a 36-minute no observed adverse effect level (NOAEL) for lethality value of 400 ppm in rats. The 2013 document notes that OHS professionals have incorporated IDLH values into risk management plans and guidance for emergency responders. For more information on IDLH values, visit the NIOSH .