An often overlooked requirement in the HCP standard (1910.95) requires each hearing protector provided by the employer be evaluated using 1910.95 Appendix B to ensure that each one will attenuate the noise level down to a prescribed exposure limit; either 90 dBA or 85 dBA if the user has suffered a standard threshold shift (STS).
This logic is similar to our analysis of our respiratory protection factors, which ensures a high enough protection factor for the degree of hazard exposure.
1910.95(j)(1) states:
| The employer shall evaluate hearing protector attenuation for the specific noise environments in which the protector will be used. The employer shall use one of the evaluation methods described in Appendix B: “Methods for Estimating the Adequacy of Hearing Protection Attenuation. |
Most of us do our sound level surveys on the A-scale and therefore when doing your evaluation subtract 7 dB from the manufacturer’s Noise Reduction Rating (NRR), and subtract the remainder from the A-weighted TWA to obtain the estimated A-weighted TWA for the ear protector.
For example, I always assume the worst when doing my evaluations. I make sure that any employee working in the facility’s loud work areas can wear the hearing protection with the lowest NRR for a full shift and still be attenuated down to 85 dBA.
Example: My worst noise area has a TWA or a Sound Level Survey reading of 110 dBA.
I then looked at what the protector offered at the workplace with the lowest manufacturer, NRR.
Let’s say its NRR is 27. I took seven (7) from this and am now at an NRR of 20. I then take 20 from the 110 noise level to 90. Now 90 dB is the PEL-TWA for noise, and we would be ok UNLESS the employee exposed to this noise has had an STS, in which case we must attenuate them down to 85 dBA; therefore, we should NOT use this protector in this area.
Two assumptions we should make:
1) do your evaluation using the highest noise readings you have from your most recent sound level survey or dosimetry readings and
2) use the 85 dBA level when doing your evaluation, or you will have to manage two different groups of employees and enforce BOTH groups as to which protectors they can and can’t wear – nearly impossible to do.
Remember, this evaluation is EXTREMELY IMPORTANT to ensure that employees working in high-noise areas are adequately protected. It is as important to our hearing as the respirator protection factors are to breathing.
NIOSH also has some GREAT aids in helping us understand this further and tools to use when doing our evaluations. Click Here for NIOSH resources. If you need help, as always I am available for FREE by phone and e-mail. You can also contact your local OSHA office or NIOSH @ 1-800-232-4636 or by e-mail.