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.
Hearing Conservation Programs - include annual audiometric testing and provision of hearing protectors.
Engineering Controls - include reducing machinery noise through redesign, replacement with quieter equipment or by reducing the transmission of noise along the path from source to receiver.
Controls - include reducing noise exposure by limiting the time an
employee is exposed to given noise levels.
1. Criteria for Engineering or Administrative Controls
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
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
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
2. OSHA Criteria for Hearing Conservation Programs
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)
D = Workday
dose in percent
1. Assume exposure of:
85 dBA for
D = 100 (5/16
+ 2/12.1 + 0.5/32) = 49.34%
2. Assume exposure of:
100 dBA for