Directives - Table of Contents
• Record Type: / Instruction
• Directive Number: / CPL 2-2.35A
• Title: / 29 CFR 1910.95(b)(1), Guidelines for Noise Enforcement; Appendix A
• Standard Number: / 1910.95(b)(1)
• Information Date: / 12/19/1983
NOTE: Although the first three (3) pages of this OSHA Instruction CPL 2-2.35A have been cancelled, Appendix A is still vaild.
Appendix A
Noise Control Guidelines
When comparing the relative degree of attenuation of personal protectors and engineering and/or administrative controls, all of the following factors in addition to the guidelines in the Field Operations Manual and Industrial Hygiene Field Operations Manual must be considered and documented in the case file:
1. Hearing Protection. Personal hearing protection must attenuate the occupational noise received by the employee's ears to within the levels specified in Table G-16 of 29 CFR 1910.95. For those employees with a standard threshold shift (STS), noise reduction must be sufficient to meet Table G-16a of 29 CFR 1910.95 (85 TWA). Hearing protectors shall be evaluated for the purposes of analyzing the benefits of engineering controls as follows:
a. Use Appendix B of 29 CFR 1910.95 to determine the laboratory-based noise reduction for a given hearing protector. b. Apply a safety factor of 50 percent; i.e., divide the calculated laboratory-based attenuation by 2. NOTE: This is a general method for taking into consideration OSHA experience and the published scientific literature, which indicate that laboratory-obtained attenuation data for hearing protectors are seldom achieved in the workplace. If a different safety factor seems appropriate in a particular instance, the ARA for Technical Support should be consulted for assistance. This procedure is not applicable, however, for determining compliance with the hearing protector attenuation requirements of the hearing conservation amendment (29 CFR 1910.95(j)). c. The adjusted noise reduction should be sufficient to meet Table G-16 or, as appropriate, Table G-16a. Depending on the specifics of the case, an exception may be appropriate when an employer is in compliance with the hearing conservation amendment and has a history of an effective hearing conservation program.
2. Hearing Loss. Documentation of any hearing loss shall include:
a. The amount of hearing ability lost and date it was recorded. NOTE: If the employer has not done so, apply age correction to audio-grams according to the guidelines in Appendix F of 29 CFR 1910.95. b. Exposure level. c. Frequency and duration of exposure. d. Length of employment. e. Explanation of any followup measures taken. f. Any other pertinent information.
3. Cost of Controls.
a. Resonability. The estimated costs for engineering controls must be reasonable and include the annualized cost of installing controls and, if available, the annual cost of their maintenance and costs due to any resulting loss of productivity or effeciency. b. Relative Permanency. In order to consider the permanency of engineering controls, compare the estimated cost for engineering controls to the estimated annual cost of a hearing conservation program multiplied by the approximate number of years the controls would be effective.
4. Employee Noise Reduction by Controls. An anticipated reduction in employee noise exposures would be considered significant if a 3 to 5 dB decrease is achieved by one or a combination of the following:
a. Source controls. b. Controlling the industrial environment (e.g., barriers, enclosures, etc.). c. Administrative controls.
5. Control Options. When evaluation control options for the purposes of this instruction, consider all types of abatement possibilities. For example:
a. Partial Use of Controls. It may be beneficial to implement some of the controls while forgoing more costly ones. b. Substitution. Abatement plans may include plans for replacing process equipment with quieter equipment that will significantly reduce exposure levels and make interim engineering controls for existing machinery impractical.
If normal conversation is difficult between two individualsstanding at arms length during noisy operations, have noiselevels been evaluated by a competent person to determine if
noise levels exceed 90 dBA as an eight-hour time-weightedaverageor 140 dB as a peak value? [29 CFR 1926.52(a)]Note: The National Institute for Occupational Safety and
Health (NIOSH) recommends a different, more protectivestandard to prevent hearing loss. Please contact NIOSH forinformation regarding their recommendations.
6.L If individuals are exposed to noise levels above 90 dBA as aneight-hour time-weighted-average, are feasible administrativeor engineering controls used to reduce the noise level tobelow 90 dBA? [29 CFR 1926.52(b)]
7. If individuals are exposed to noise levels above 90 dBA as aneight-hour time-weighted-average, are they required to wearhearing protection? [29 CFR 1926.52(b) and 1926.101(a)]
8. If individuals are exposed to noise levels above 90 dBA as aneight-hour time-weighted-average, is there a continuing,effective hearing conservation program being administered?[29 CFR 1926.52(d)(1)]
9. If hearing protection is used, is the type of hearing protectionfitted or determined by a competent person? [29 CFR1926.101(b)]
10. Is the use of plain cotton as hearing protection prohibited?[29 CFR 1926.101(c)]
1926.52Occupational noise exposure.
(a) Protection against the effects of noise exposure shall be provided when the sound levels exceed those shown in Table D-2 of this section when measured on the A-scale of a standard sound level meter at slow response.
(b) When employees are subjected to sound levels exceeding those listed in Table D-2 of this section, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels within the levels of the table, personal protective equipment as required in subpart E, shall be provided and used to reduce sound levels within the levels of the table.
(c) If the variations in noise level involve maxima at intervals of 1 second or less, it is to be considered continuous.
(d)(1) In all cases where the sound levels exceed the values shown herein, a continuing, effective hearing conservation program shall be administered.
Table D-2--Permissible Noise Exposures
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Sound level
Duration per day, hours dBA slow
response
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8...... 90
6...... 92
4...... 95
3...... 97
2...... 100
1\1/2\...... 102
1...... 105
\1/2\...... 110
\1/4\ or less...... 115
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(2)(i) When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. Exposure to different levels for various periods of time shall be computed according to the formula set forth in paragraph (d)(2)(ii) of this section.
(ii) Fe = (T1/L1)+(T2/L2)+ · · · + (Tn/Ln)
Where:
Fe = The equivalent noise exposure factor.
T = The period of noise exposure at any essentially constant level.
L = The duration of the permissible noise exposure at the constant level (from Table D-2).
If the value of Fe exceeds unity (1) the exposure exceeds permissible levels.
(iii) A sample computation showing an application of the formula in paragraph (d)(2)(ii) of this section is as follows. An employee is exposed at these levels for these periods:
110 db A 1/4 hour.
100 db A 1/2 hour.
90 db A 1 1/2 hours.
Fe = ( 1/4/ 1/2)+( 1/2/2)+(1 1/2/8)
Fe = 0.500+0.25+0.188
Fe = 0.938
Since the value of Fe does not exceed unity, the exposure is within permissible limits.
(e) Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.