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. This 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. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

December 07, 1998

Mr. Jesse L. McDaniel, CSP
Countrymark Cooperative, Inc.
950 North Meridian Street
Indianapolis, Indiana 46204-3909

Dear Mr. McDaniel:

This is in response to you letter dated May 11, where you have asked for an interpretation of the Occupational Safety and Health Administrations (OSHA) Storage and Handling of Anhydrous Ammonia standard, CFR 1910.111 and the revised Respiratory Protection standard, CFR 1910.134. We apologize for the long delay in getting this response to you.

You have asked a question that concerns a provision in the anhydrous ammonia standard. The Federal OSHA standard requires that at stationary storage installations, the employer must have at least two suitable gas masks with ammonia canisters. According to your letter, some state agencies have requirements for your industry as well, and you have asked would Federal OSHA regulations would take precedence? Generally, Federal OSHA regulations are not preempted by state law. States may establish laws which are more restrictive and can also regulate in areas where the federal government does not have any standards. Your question is being answered here from the Federal OSHA perspective. Both Minnesota and Indiana are State Plan states. In these states, it may depend on state law whether state agriculture law preempts state OSH law. You will need to make the appropriate inquiries with the individual states to obtain their requirements.

Your second question is, does a full facepiece respirator with ammonia cartridges meet the definition of a "gas mask"? A full facepiece respirator with ammonia cartridges is not the same as a gas mask. The National Institute for Occupational Safety and Health NIOSH) defines a gas mask as a mask that consists of a full facepiece and either chin-style or front or back-mounted canisters with associated connections. A full facepiece respirator with ammonia cartridges does not meet this definition.

Thank you for your interest in safety and health. If you have any additional questions, please call OSHA's Office of Health Compliance Assistance at (202) 693-2190.


Richard Fairfax
Directorate of Compliance Programs