Isocyanate respirator approval in auto body spray painting

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

June 13, 1996

Robb Menzies, President
ACE Systems, Ltd.
[Recipient address omitted]
Dear Mr. Menzies:

We are in receipt of your letter forwarded to our office from Dr. Gerry Ryan, Assistant Regional Administrator for Technical Support in the Occupational Safety and Health Administration (OSHA) Region VIII. This letter will only address the respirator concerns expressed in your original letter to Region VIII. We understand that the other issues you raised were addressed by Dr. Ryan in his response to you dated February 27, 1996.

Your request first of all is not without precedent. We are aware that there have been several studies in the literature that support the use of organic vapor charcoal filters as effective against isocyanates. As you are aware, OSHA requires the National Institute for Occupational Safety and Health (NIOSH) certification of respirators and that for contaminants with poor warning properties NIOSH specifies that a supplied air respirator must be used. NIOSH has, however, approved the use of an end-of-service-life indicator for mercury vapor. Mercury vapor also has poor warning properties.

OSHA, in the case of benzene, with its poor warning properties, has allowed the use of organic vapor cartridges with a half mask elastomeric respirator (29 CFR 1910.1028). In the preamble to the benzene standard, OSHA stated the following:

"For lower concentrations of benzene, OSHA proposes to permit the use of air purifying respirators provided that the filter element is replaced at the beginning of each workshift. Benzene has poor warning properties at low levels, and OSHA is aware that MSHA/NIOSH would not approve the use of air-purifying respirators in this situation because the users would be unable to detect the benzene if breakthrough occurs. However, OSHA believes that filter elements of the type approved by MSHA/NIOSH for use with organic vapors would provide sufficient service life for the intended application as prescribed in Table 1 if replaced with the required frequency."

You indicated that, based upon your conversations with NIOSH, their certification of your specially treated charcoal filter with an optional end-of-service-life indicator would be delayed. The delay is due to resource demands posed by a backlog of certification requests resulting from NIOSH's recently revised certification procedures that are codified at 42 CFR Part 84. We have contacted NIOSH concerning this issue and suggest that since the unit apparently is already patented in the United States and has been sent for certification in Canada, the unit should also be submitted to NIOSH for certification, unless problems with the unit have surfaced in the Canadian certification process. We spoke with NIOSH regarding your letter and were told that you should contact Larry Reed with NIOSH in Cincinnati, Ohio. Mr. Reed can be contacted at (513) 533-8304 or FAX at (513) 533-8588. A copy of your letter and this response will be forwarded to Mr. Reed.

Concerning our acceptance of a Canadian approval, we are not aware of any respirator certification procedure in Canada. It has been our understanding that in Canada, the standard practice is to accept and use the NIOSH respirator certification process. If however, Canada does certify respirators and certifies your charcoal filters and the end-of-service-life indicator, that testing and certification information should be provided to NIOSH along with your application. Our respirator standard specifies only NIOSH approval and certification. OSHA would not be able to accept the certification of a respirator by another governmental agency outside the United States unless a cooperative agreement or a memorandum of understanding was reached between NIOSH and the certification group in another country.

One other point must be mentioned. OSHA can only require the use of respiratory protection where we can document that an overexposure has or is likely to occur. In the case of spray painting in autobody shops, our sampling data from this industry has found virtually no overexposures to isocyanates. Workers could currently wear a half mask respirator with organic vapor cartridges and be within our requirements provided the employees were not exposed to isocyanates above our permissible exposure limits. An employer should, under these circumstances, conduct periodic monitoring for isocyanates to assure that the worker exposure to isocyanates remain below the permissible exposure limit.

We hope this information provides you some assistance to a complicated issue. If we can be of any further assistance please contact the Office of Health Compliance Assistance at (202) 219-8036.

Sincerely,

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

[Earlier regional OSHA response reproduced on OSHA page; omitted here.]