OSHA updated a 2017 Letter of Interpretation in January 2021 and it is causing quite a stir in the anhydrous ammonia (NH3) fertilizer industry and could have impacts on other industries that use NH3. In this revised LOI, OSHA states…
… Therefore, OSHA believes it is possible, and indeed likely, that any given release of anhydrous ammonia in your scenario will necessitate an emergency response in accordance with the requirements of 29 CFR 1910.120(q). Extremely small vapor releases, such as minor valve packing leakage and similar releases where exposures in the breathing zone of the employee would be less than the PEL and there is no risk of a catastrophic release, may be considered incidental.
I wish to explain the silliness of using the Permissible Exposure Limits to define an “emergency”.