November 20, 1987

Mr. Brent Miller
Metco Technical Field Engineer
Weldwell New Zealand 2581

Dear Mr. Miller:

This is in response to your inquiry of October 30, to the U.S. Occupational Safety and Health Administration (OSHA) requesting information on the OSHA occupational noise exposure standard and publications regarding metal spray operations safety (presumably from the effects of noise). Your letter was forwarded to the Directorate of Technical Support for reply.

The OSHA 29 CFR 1910.95 Occupational Noise Exposure standard limits employee noise exposure to 90 dB(A) averaged over an eight hour workday measured at the employee's hearing zone. The allowable exposure time is halved for each 5 dB of increased exposure - thus 95 dB(A) is allowed for four hours, 100 dB(A) for two hours, etc. Furthermore, the standard mandates employee inclusion in a hearing conservation program if the employee is exposed to an average of 85 dB(A) or more for a workday.

Enclosed for your information is a translation of an article published by the Erisman Institute of Health, Moscow, U.S.S.R., "Noise in Plasma Spray Coating and Hygienic Measures to Improve the Technique." Also enclosed is a copy of a technical bulletin from Metco, Inc., Westbury, L.I., New York, U.S.A., that describes a typical spray room used in the control of processes such as metal spraying. Please note that use of a special room is probably the most complete engineering control available for metal spraying noise emissions. It may be possible in certain applications to achieve favorable noise emission reductions using simpler controls such as employee isolation booths or source barriers.

Please contact this office if further information is required.

Sincerely,



Edward J. Baier Director
Directorate of Technical Support