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.

June 27, 1997

Mr. Liwen Kao
Booz-Allen & Hamilton Inc.
Suite 650
523 West Sixth Street
Los Angeles, CA 90014

Dear Mr. Kao:

This is in response to your letter of March 31, regarding the applicability of 29 CFR 1910.103, Hydrogen, to fuel cell buses which operate on compressed hydrogen fuel that is contained in fuel storage cylinders.

In your letter, you indicated that the Chicago Transit Authority (CTA) will be acquiring three fuel cell buses which operate on compressed hydrogen fuel, in order to evaluate the feasibility of fuel cell buses for transit applications as part of a demonstration program. In this particular situation, it is most significant to note that according to 29 United States Code, Section 652(5), the Occupational Safety and Health Administration (OSHA) does not have jurisdiction over the CTA, since the CTA is a local government agency and Illinois is not an OSHA State-Plan-State.

OSHA Standard, 29 CFR 1910.103 does not apply to fuel-cell-buses. The following is provided to you as information only. Paragraph (a)(1) of §l 910.103 defines hydrogen systems and they include containers, pressure regulators, safety relief devices, manifolds interconnecting piping and controls. The scope of §1910.103, paragraph (a)(2), states, "this section applies to the installation of hydrogen systems on consumer premises where the hydrogen supply to the consumer premises originates outside the consumer premises and is delivered by mobile equipment."

You indicated that fuel cell buses will be parked indoors, in bays that have been specially modified for hydrogen, at an existing maintenance facility. You also mentioned that these buses will hold more than 21,000 standard cubic feet of gaseous hydrogen at a pressure of 3,600 psi.

As you may know, fuel cells could unexpectedly release hydrogen which would disperse readily, and hydrogen is known to cause serious injury or death. Therefore, you may wish to consider §1910.103 as a safety reference for the confinement of the fuel cells on buses; as well as their associated fueling and maintenance facilities, so that the hazards associated with unexpected events of release would be minimized or avoided. Electrical equipment safeguards and open flames must be considered independent of the existing volume of hydrogen. Further, additional information can be found in the National Fire Protection Association's (NFPA's) Pamphlets 220, 51, 566, and NFPA 88B.

As you noted, Table H-1 of §l 910.103 would prohibit the location of gaseous hydrogen systems in excess of 15,000 cubic feet inside buildings not in a special room and exposed to other occupancies. As we indicated before, the standard is not applicable to the fuel cells on the buses. Please note, however, that the buses should not be parked inside the maintenance facility, if this is feasible. Since your letter did not indicate where the fuel facility is located and how these buses will be re-fueled, we must bring to your attention the danger of conducting such activities inside buildings.

Finally, in the absence of regulations regarding this issue, and due to the fact that the fuel cell buses are in a state of research and development with a few operating buses in existence, OSHA would be most interested in obtaining a copy of your final safety report, as you move forward with the Chicago Transit Authority demonstration program.

We appreciate your interest in occupational safety and health. If you have questions regarding the preceding, please contact Alcmene Haloftis of my staff at 202-219-8031, ext. 119.


John B. Miles, Jr., Director
Directorate of Compliance Programs