§ 57.5050 - Exposure limits for noise.

(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 for type 2 meters contained in American National Standards Institute (ANSI) Standard S1.4-1971, “General Purpose Sound Level Meters,” approved April 27, 1971, which is hereby incorporated by reference and made a part hereof, or by a dosimeter with similar accuracy. This publication may be obtained from the American National Standards Institute, Inc., 1430 Broadway, New York, New York 10018, or may be examined in any Metal and Nonmetal Mine Health and Safety District or District Office of the Mine Safety and Health Administration.

Permissible Noise ExposuresDuration per day, hours of exposureSound level dBA, slow response890692495397210011/210211051/21101/4 or less115 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 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:

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

(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 protection equipment shall be provided and used to reduce sound levels to within the levels of the table.