In March 2026, NIOSH issued a formal request for information to update the IDLH Value Profiles. While ammonia has an established IDLH of 300 ppm, the agency is seeking new toxicology and human health effects data to refine these values.
The Focus: The RFI specifically looks for “weight-of-evidence” data on how chemical modes of action—such as the rapid desensitization of olfactory receptors—impact a worker’s ability to self-evacuate.