1. A. No employee shall be permitted an exposure to noise in excess of that specified in the table below. Noise level measurements shall be made using a sound level meter meeting specifications contained in “American National Standard Specification for Sound Level Meters,” which is hereby incorporated by refer­ence and made a part hereof, or by a dosimeter with similar accuracy. This publication may be examined in the Arizona State Mine Inspector’s office.

   PERMISSIBLE NOISE EXPOSURES

   Duration Per Day Hours of Exposure	Sound Level Dba Slow Response
   8	90
   6	92
   4	95
   3	97
   2	100
   1 1/2	102
   1	105
   1/2	110
   1/4 or less	115

   No exposure shall exceed 115 dBA. Impact or impulsive noises shall not exceed 140 dB, peak sound pressure level.

   NOTE: When the daily exposure is composed of two or more periods of noise exposure at different levels, their combined effect shall be considered rather than the indi­vidual effect of each. If the sum

   (Cl/Tl) + (C2/T2) + . . . (Cn/Tn)

   exceeds unity, then the mixed exposure shall be consid­ered to exceed the permissible exposure. Cn indicates the total time of exposure at a specified noise level, and Tn indicates the total time of exposure permitted at that level. Interpolation between tabulated values may be determined by the following formula:

   log T = 6.322 - 0.0602 SL

   There T is the time in hours and SL is the sound level dBA.

2. B. When employees’ exposure exceeds that listed in the above table, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce exposure to within per­missible levels, personal protective equipment shall be pro­vided and used to reduce sound levels to within the levels of the table.

Historical Note

Adopted effective April 7, 1976 (Supp. 76-2). Amended effective August 18, 1980 (Supp. 80-4).