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.

November 19, 1990


                   OFFICE OF FIELD PROGRAMS


SUBJECT:            Hazard Communication Standard and Ozone- Generating

This is in response to your memorandum of September 19, regarding the applicability of the Hazard Communication Standard (HCS) to workplace machinery and operations that generate ozone as a by- product during normal operation. Your memo specifically mentioned the production of ozone generated during welding operations, or produced by high energy or photocopier machines, etc.

Although by-products are covered by the HCS, the standard only requires chemical manufacturers or distributors to anticipate the downstream workplace uses of their chemical products and as part of their hazard determination procedures, account for worker exposure to hazardous by-products that may be formed during normal conditions of use. Under the HCS, the manufacturers of welding rods or other chemical products that are utilized during welding and other operations which are capable of resulting in employee exposures would be responsible for chemical hazard information (MSDSs, labels, etc.) to be transmitted to downstream employers.

However, manufacturers of "high energy machines", welding machines or photocopiers are not considered to be chemical manufacturers under the HCS since they produce machines and not chemicals, for use or distribution to downstream employers. Because ozone is not generated by the welding rod or flux, but rather results from the ionization of the air surrounding the arc or high voltage gap, ozone is not a by-product of the welding rod or photocopier chemical but of the welding or photocopying process. Ozone generated in this fashion would not fall within the scope of 29 CFR 1910.1200(b)(1).

The newly revised Hazard Communication Compliance Directive, CPL 2-2.38C (effective date: October 22, 1990), contains the following language relative to 29 CFR 1910.1200(b)(2) which provides further guidance on hazard communication and workplace exposures to hazardous substances such as you described in your memo (see Appendix A, page A-2):

The phrase "known to be present" is essential to understanding the scope of the standard. If a hazardous chemical is known to be present by the chemical manufacturer or the employer, it is covered by the standard. This includes chemicals to which employees may be exposed during normal operations or in a foreseeable emergency. This means that even though an employer did not create the hazard, such as silica exposure during concrete demolition, or the hazards of exposure to the chemicals brought onto a multi- employer worksite by other employer(s), the standard applies and the employer whose employees are exposed to chemicals known to be present should include hazard communication information about these exposure situations in his workplace hazard communication program.

In the ozone generating process you described, the presence of ozone in the workplace should be addressed in the employer's hazard communication program. Application of this provision is, of course, dependent on whether exposure to ozone is the result of normal conditions of use, such as photocopying constantly during the day (i.e., a worker's job assignment) or exposures that welders could normally expect to occur on a routine basis. In situations where this provision would apply, employers would not have to "produce" an MSDS or a label, but should provide information in their hazard communication program to inform their employees "about the hazardous chemical to which they are exposed." Employers may, of course, use their existing hazard communication programs to communicate information on these types of hazards to their employees as per paragraph (e)(3) of the HCS.

This new language in the hazard communication directive describes a previously unused "should" obligation for employers who expose their employees to hazardous substances, in situations where they do not create the hazards or bring them onto the worksite. This interpretation of the scope and application section of the standard will allow OSHA staff to encourage employers to include chemical hazard information in their existing hazard communication programs. This may be accomplished as part of an employer's abatement of written program violations or through the Agency's encouraging of the employer to address chemical hazards "known to be present" in their employee training sessions.

We hope this clarifies this issue for you. If you have any further questions, please feel free to contact Melody Sands of my staff at (FTS) 523-8036.

September 19, 1990

                Directorate of Compliance Programs

FROM:            LINDA R. ANKU Regional Administrator

SUBJECT:         Hazard Communication Standard

Questions have arisen concerning whether ozone which is generated during the normal operation of machinery is covered by the Hazard Communication Standard. The ozone would be generated as a by-product of the operation such as welding, high energy machinery, photocopier machines, etc.

It has been this office's understanding that ozone generated in the aforementioned manner would not be covered under the Hazard Communication standard since the ozone is not generated by a chemical process but rather as a by-product of electrical current. If the ozone referenced would be considered to be covered by the standard then the portions of the standard that would be applicable should be defined. Obviously, labels would not be required but would the employer be required to generate a material safety data sheet? Your comments on this issue are requested.

Please contact Jim Johnston of my staff (FTS 596-1201) if there are any questions.