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.

March 4, 1993

Mr. Matthew V. McFarland
Safety & Health Management Consultants, Inc.
161 William Street
New York, New York 10038

Dear Mr. McFarland:

This is in response to your inquiry of January 19, concerning the scope of Hazard Communication under the safety and health regulations for construction, 29 CFR 1926.59. Specifically, you question whether inert gas, an asphyxiant, is covered by the standard.

Inert gas is normally present in the workplace in compressed gas cylinders and is covered by virtue of being a compressed gas. Such cylinders must be carefully handled as the compressed gases present certain physical hazards - particularly in the event of an emergency, such as a fire. In construction the most frequent documented origin of a fire in a burning and cutting operation is when molten slag burns through the welding hose, causing free flowing fuel gas to ignite and potentially spread to other volatile gas cylinders. Furthermore, the sudden release of pressure from a compressed gas bottle can convert a cylinder into an uncontrollable rocket.

It is the responsibility of the manufacturer to perform the hazard determination of a substance. Substances such as methane and ethane, are pharmacologically "inert," belonging to a group of gases called simple asphyxiants. These gases can be tolerated at high concentrations in the air without producing systemic effects. At high concentrations, however, these substances dilute or exclude oxygen from the air however, toxicity results from oxygen deprivation or asphyxia. Furthermore, a simple asphyxiant such as methane is odorless with its chief danger being an explosion hazard.

Accordingly, toxicity has been established in inert gases and the manufacturer, importer, and/or distributor has the duty of performing a complete hazard determination.

We hope this information is helpful. If you have any further questions please feel free to contact us at (202) 219-8036.


Roger A. Clark, Director
Directorate of Compliance Programs

January 19, 1993

Ms. Dorothy Strunk
Acting Assistant Secretary
Occupational Safety & Health
U.S. Department of Labor
Washington, DC 20210

Dear Admin. Strunk:

This letter is to inquire about the scope of the Hazard Communication Standard 1926.59. In reference to this standard, I question whether an inert gas, which is only a simple asphyxiant, is covered by the standard.

The standard defines a Hazardous Chemical as one which is a physical or health hazard. Since an inert gas poses no physical hazard, unless compressed, the only way it could be covered by the standard is to be a health hazard. The standard defines a health hazard as chemicals in categories such as carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents which act on the hematopoietic system, and agents which damage the lungs, skin, eyes, or mucous membranes. Since an inert gas which is a simple asphyxiant does not fall into any of these categories, it would appear that it does not meet the definition of a health hazard.

From the explanation above, it appears inert gases are not covered by the standard. Is this a defect in the standard?

I would appreciate being informed of the position OSHA takes regarding this matter as soon as possible.


Matthew V. McFarland