Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

March 15, 1995

Hasmukh C. Shah, Ph.D. Manager,
Vinyl Chloride Panel Chemical
Manufacturers Association
2501 M Street, N.W.
Washington, D.C. 20037

Dear Dr. Shah:

This is in response to your letter of July 26, 1994, requesting clarification of the application of the Vinyl Chloride Standard (29 CFR 1910.1017) and the Hazardous Waste Operations and Emergency Response standard (29 CFR 1910.120; HAZWOPER). Please accept my apology for the delay in this reply.

You have questioned the practicality of complying with 1910.1017(g)(5)(i) which reads as follows:

"Entry into unknown concentrations or concentrations greater than 36,000 ppm (lower explosive limit) may be made only for the purposes of life rescue;"

You have expressed your understanding that the more updated emergency response provisions of 1910.120(q) do not apply since HAZWOPER states in 1910.120(a)(2) that where there is a conflict or overlap between standards the provision more protective of employee health and safety applies.

We do not agree with your understanding. HAZWOPER allows entry into unknown atmospheres or into concentrations greater than the lower explosive limit for emergency response purposes. However, as you point out in your letter, failure to respond to leaks of vinyl chloride could itself lead to catastrophic failures or explosions that could be life threatening. Thus, we interpret the HAZWOPER provisions to be more protective to worker safety and health. We will be notifying our enforcement offices to enforce HAZWOPER section (q) instead of 1910.017(g)(5)(i).

We hope this information is helpful. Thank you for bringing this matter to our attention.


Ruth McCully, Director
Office of Health Compliance Assistance

July 26, 1994

Ms. Ruth McCulley Office of Health Compliance Assistance Occupational Safety and Health Administration United States Department of Labor, Room N346l 200 Constitution Ave., NW Washington, D.C. 20210

RE: Vinyl Chloride Standard

Dear Ms. McCulley:

On January 4, 1994, you and MaryAnn Garrahan met with Mr. Peter de la Cruz and myself on behalf of the CMA Vinyl Chloride Panel. Among other matters, we discussed a provision in the vinyl chloride standard addressing entry into areas of unknown concentrations or concentrations greater than 36,000 parts per million (ppm) 29 C.F.R. Section 1910.1017(g)(5)(i). At the meeting, you referred to a number of high priority commitments as well as the operation of several task forces within the Agency. Given the passage of time, I thought it might be convenient to close this matter by providing you with a letter briefly summarizing our meeting.

We noted that there may be a relationship between the vinyl chloride standard and the Hazardous Waste Operations and Emergency Response Rule (HAZWOPER), 29 C.F.R. Section 1910.120. Ms. Garrahan referred to language the Agency's HAZWOPER compliance directive which indicated that, when there is a conflict or overlap of coverage between standards, the more specific and protective provision applies. In her view, this meant that the language of the vinyl chloride standard was controlling, rather than HAZWOPER. Thus, the issue is one of interpreting the vinyl chloride standard.

In discussing the vinyl chloride standard, I reported that it is the practice of the vinyl chloride manufacturing companies that emergency responders are properly trained to enter the environment containing vinyl chloride, and they use appropriate personal protective equipment. Responders would strive to minimize any hazard associated with the situation by, for example, using water shields to dilute or disseminate any vinyl chloride monomer to which responders might be exposed. Mr. de la Cruz and I also stressed that failure to respond to leaks of vinyl chloride could itself lead to catastrophic failures or explosions that might be life threatening.

You and Ms. Garrahan were unaware of any relevant interpretations of the vinyl chloride standard by the Agency addressing this particular provision. None of the meeting participants were aware of any citations concerning responders into unknown concentrations of vinyl chloride or concentrations greater than 36,000 ppm. You and Ms. Garrahan did not suggest that our reading of the standard, which would permit properly trained and equipped responders to take corrective action, was unreasonable. However, you also made it clear that you were not expressing an opinion on the correctness of our interpretation. You indicated that prior to expressing an opinion on behalf of the Agency, you would like to review the rulemaking record and the Agency files. We would appreciate your informing us of the results of your research or preliminary thoughts.

Mr. de la Cruz and I, as well as the Vinyl Chloride Panel, appreciate your meeting with us in January and trust that this letter will serve as an adequate summary of our meeting. If you have any comments or questions, please do not hesitate to call me at 202/887-1192.


Hasmukh C. Shah, Ph.D. Manager,
Vinyl Chloride Panel