Letters of Interpretation | Occupational Safety and Health Administration

Letters of Interpretation

OSHA requirements are set by statute, standards, and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. Each letter constitutes OSHA's interpretation of the requirements discussed.

Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information.

These letters of interpretation and the standards they address may not apply to OSHA State Plans. State Plans are required to have standards and enforcement programs that are at least as effective as OSHA's and may have different or additional requirements. Please see OSHA-approved State Plans for more information.

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Date	Title	Standard Number
06/02/1994	Highly Hazardous Chemical's anhydrous ammonia (NH(3)).	1910.119
06/01/1994	HHC standard as it applies to threshold quantity.	1910.119
05/25/1994	Highly Hazardous Chemicals, types of hardware that see contact with explosives.	1910.119
05/18/1994	Highly Hazardous Chemicals as it applies to aqueous solutions of hydrofluoric acid.	1910.119
04/28/1994	Highly Hazardous Chemicals as it applies to what constitutes the boundaries of a process.	1910.119
04/22/1994	Highly Hazardous Chemicals as it applies to threshold quantity (TQ) of HHCs.	1910.119
04/07/1994	Highly Hazardous Chemicals, hydrocarbon fuels.	1910.119
03/31/1994	Highly Hazardous Chemicals standard, Tertiary Butyl Hydroperoxide (TBHP).	1910.119
03/21/1994	Highly Hazardous Chemicals, hydrochloric acid.	1910.119
03/16/1994	Highly Hazardous Chemicals as it applies to flammable liquid from a stationary tank.	1910.119
03/10/1994	Highly Hazardous Chemicals as it applies to a covered process.	1910.119
03/09/1994	Highly Hazardous Chemicals as it applies to operating procedures and certify on an annual basis.	1910.119
02/15/1994	Remote distance, close proximity and other PSM questions.	1910.119
01/31/1994	Highly Hazardous Chemicals as it applies to solid propellant rocket motors.	1910.119
01/31/1994	Highly Hazardous Chemicals as it applies to toxic or reactive chemical mixtures which are not explosive and which are not flammable liquids or gases.	1910.119
01/28/1994	Highly Hazardous Chemicals applies to aqueous solutions of Hydrogen Fluoride.	1910.119
01/26/1994	Highly Hazardous Chemicals as it applies to "Dowtherm".	1910.119
12/30/1993	Applicability of the Process Safety Management manufacturing processes involving workplace explosives.	1910.109, 1910.119
12/30/1993	HHCs as it applies to ethylene oxide (ETO).	1910.119
12/30/1993	HHCs as it applies to manufacturing processes involving workplace explosives.	1910.119