California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 7 - General Industry Safety Orders › Group 15 - Occupational Noise and Ergonomics › Article 105 - Control of Noise Exposure › Appendix E - Methods for Estimating the Adequacy of Hearing Protector Attenuation

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
I. For employees who have experienced a standard
						  threshold shift, hearing protector attenuation must be sufficient to reduce
						  employee exposure to a TWA of 85 dB. Employers must select one of the following
						  methods by which to estimate the adequacy of hearing protection
						  attenuation.
II. The most convenient method is the Noise Reduction
						  Rating (NRR) developed by the Environmental Protection Agency (EPA). According
						  to EPA regulation, the NRR must be shown on the hearing protector package. The
						  NRR is then related to an individual worker's noise environment in order to
						  assess the adequacy of the attenuation of a given hearing protector. This
						  Appendix describes four methods of using the NRR to determine whether a
						  particular hearing protector provides adequate protection within a given
						  exposure environment. Selection among the four procedures is dependent upon the
						  employer's noise measuring instruments.
III. Instead of using the NRR, employers may evaluate
						  the adequacy of hearing protector attenuation by using one of the three methods
						  developed by the National Institute for Occupational Safety and Health (NIOSH),
						  which are described in the "List of Personal Hearing Protectors and Attenuation
						  Data," HEW Publication No. 76-120, 1975, pages 21-37. These methods are known
						  as NIOSH methods #1, #2 and #3. The NRR described below is a simplification of
						  NIOSH method #2. The most complex method is NIOSH method #1, which is probably
						  the most accurate method since it uses the largest amount of spectral
						  information from the individual employee's noise environment. As in the case of
						  the NRR method described below, if one of the NIOSH methods is used, the
						  selected method must be applied to an individual's noise environment to assess
						  the adequacy of the attenuation. Employers should be careful to take a
						  sufficient number of measurements in order to achieve a representative sample
						  for each time segment.
NOTE: The employer must remember that calculated
						  attenuation values reflect realistic values only to the extent that the
						  protectors are properly fitted and worn.
IV. When using the NRR to assess hearing protector
						  adequacy, one of the following methods must be used:
(a) When using a dosimeter that is capable of
						  C-weighted measurements:
(1) Obtain the employee's C-weighted dose for the
						  entire workshift, and convert to TWA (see Appendix A).
(2) Subtract the NRR from the C-weighted TWA to obtain
						  the estimated A-weighted TWA under the ear protector.
(b) When using a dosimeter that is not capable of
						  C-weighted measurements, the following method may be used:
(1) Convert the A-weighted dose to TWA (see Appendix
						  A).
(2) Subtract 7 dB from the NRR.
(3) Subtract the remainder from the A-weighted TWA to
						  obtain the estimated A-weighted TWA under the ear protector.
(c) When using a sound level meter set to the
						  A-weighting network:
(1) Obtain the employee's A-weighted TWA.
(2) Subtract 7 dB from the NRR, and subtract the
						  remainder from the A-weighted TWA to obtain the estimated A-weighted TWA under
						  the ear protector.
(d) When using a sound level meter set on the
						  C-weighting network:
(1) Obtain a representative sample of the C-weighted
						  sound levels in the employee's environment.
(2) Subtract the NRR from the C-weighted average sound
						  level to obtain the estimated A-weighted TWA under the ear
						  protector.
1.
						  Amendment filed 10-3-83; effective thirtieth day thereafter (Register 83, No.
						  41).
Note: Authority cited and Reference: Section
							 142.3, Labor
							 Code.