U.S.
Occupational Safety & Health Administration - OSHA - Standards
As of August 1981, OSHA noise exposure standards consist of a two-stage program where hearing conservation measures become mandatory at 85 dBA for an 8-hour day but feasible engineering or administrative noise controls are required when exposures exceed 90 dBA.
Feasible administrative or engineering controls shall be utilized if noise dose D is greater than 1.0 in accordance with the following equation: D = C1/T1 + C2/T2 + CN/TN where:
Examples: 1. For an
8 hour day at constant noise levels, 90 dBA is the maximum allowable level.
100 dBA for 2 hours, 90 dBA for 6 hours Engineering or administrative controls are necessary to reduce noise dose to unity. 3. Assume exposure of: 100 dBA for
1 hour Exposure below 90 dBA does not contribute of OSHA noise "dose" for administrative or engineering controls to be employed. Therefore: D = ½
+ 4/8 = 1.00
Employers shall administer continuing, effective hearing conservation programs wherever employee noise exposures equal or exceed an 8-hour time weighted average of 85 dBA or, equivalently, a dose or 50% measured according to the following equation: D = 100 (C1/T1 + C2/T2 + C3/T3 + CN/TN) where: D = Workday
dose in percent
Examples: 1. Assume exposure of: 85 dBA for
5 hours D = 100 (5/16
+ 2/12.1 + 0.5/32) = 49.34% 2. Assume exposure of: 100 dBA for
1 hour D = 100 (1/2
+ 4/8 + 3/16) = 118.75% |