Do you have a hearing conservation program? How did you decide who should be included in the program? Are you in compliance with OSHA’s noise standard? In this blog post I will discuss common pitfalls in hearing conservation programs.
Pitfall #1: Using Only a Sound Level Meter to Determine Noise Levels
Using a sound level meter can be helpful in documenting noise levels, and it is allowed by OSHA for noise sampling. But sound level meters are not the best way to sample when the goal is to determine inclusion or exclusion in the hearing conservation program. When you take a noise reading at a work station with a sound level meter, you are measuring the current level at that moment. This measurement does not include the full day or other exposures that employee has over the course of her day, including the quiet times.
Over the years of performing noise studies, I have found that many companies include people in the hearing conservation program on the basis of sound level meter measurements. This sounds like a good idea on the surface, right? It’s usually a worst case scenario estimate of the noise level since we generally take it at the loudest point. The problem is that for many employees, if you would have instead used a noise dosimeter and sampled over the course of the day, you may have found that the employee’s actual time weighted average exposure to noise is below 85 dBA. This means that this employee does not belong the hearing conservation program. If this person has a standard threshold shift (STS), since they have been placed in the hearing conservation program, you may now have an OSHA recordable case and/or a workers’ compensation claim. This may be true even if the person’s real noise exposure comes from extracurricular activities like hunting, loud music, etc.
Remember, OSHA considers standard threshold shifts to be work related if the 8 hour time weighted average (TWA) is 85 dBA or higher. But if you did not obtain a TWA using noise dosimetry, and instead placed the employee in hearing conservation based on the sound level meter reading, this is the only exposure estimate you have. Once the employee has been placed into the hearing conservation program, you must comply with the OSHA standard unless you can re-sample to show that the employee should not be in the program.
Pitfall #2: You Did Not Notify Employees of Their Sampling Results (or You Can’t Prove You Did)
Once you complete your noise sampling, OSHA requires that you notify employees of their sample results. It is best to do this in writing and have employees sign the notification so you can prove that you did it, in case you ever need to. Don’t forget to notify all employees that you represented in the sampling. For example, if you sample an assembly area that has 10 employees all doing the same task, and you choose to sample only 3 of the 10, they should all be notified of the exposure. In other words, the three employees you sampled represent all ten employees.
Pitfall #3: You Did Not Re-Sample When Conditions Changed
Annual noise sampling is not required by OSHA. OSHA requires re-sampling for noise when conditions change. Some of the factors that may cause conditions to change could be additional processes or machines added to an area, a change in the way the work is performed, additional employees performing work, etc. You should sample noise again if you have reason to believe that conditions changed to the extent that the noise levels you obtained in your baseline sampling may not be accurate. You want to be sure that everyone who should be included in your hearing conservation program is included.
Pitfall # 4: You Did Not Consider Engineering Controls; Instead You Handed Out Ear Plugs
The OSHA Noise Standard 29 CFR 1910.95 states that if employees are exposed to noise over the PEL, “feasible administrative or engineering controls shall be utilized”. This means that you are not in compliance by simply handing out ear plugs. Could employee rotation reduce overall noise exposures? Can engineering controls such as isolating the process or the isolating the employee reduce exposure levels? Can installation of sound dampening materials and proper maintenance of equipment reduce noise levels? You need to consider long-term controls rather than just relying on ear plugs. Remember, your goal is to reduce the number of people in the hearing conservation program, and the way to do that is by reducing noise levels below 85 dBA.
Hearing protection is only effective if it is worn properly, and if it is appropriate for the noise level that it is used in. And if you have been in the field, you have probably seen just as many ear plugs hanging out of ears and I have. (Not to mention the ones that were cut in half to make it look like they were being worn properly!) This fact brings me to my last pitfall for this post:
Pitfall #5: You Did Not Consider NRR Values and/or Did Not De-rate the Hearing Protection You Selected
Since we are required to sample on the A scale, but Noise Reduction Rating levels (NRR) are based on the C scale, OSHA requires us to “de-rate” hearing protection, and determine attenuation (actual noise reduction based on wearing the ear plugs). Therefore, it is not enough to use the NRR on the ear plug box and subtract that number from the employee’s noise exposure to determine the actual noise exposure. Instead, OSHA requires (in Appendix B of the Noise Standard) us to first de-rate the hearing protection by subtracting 7 from the NRR value. In the OSHA Technical Manual they also “strongly recommend applying a 50% correction factor” to compensate for the fact that all employees do not correctly wear the hearing protection. (Note: Applying the 50% correction factor is not mandatory, but is best practice.)
Here’s an example of how this would work:
You select hearing protection with an NRR value of 37 and your measured noise level is 95 dBA. First de-rate the NRR by subtracting 7.
Next (to apply the 50% correction factor): 30 x 0.5 = 15
Finally, subtract 15 from the noise level you measured in the work area:
Therefore we are estimating that if this employee wears these ear plugs in the 95 dBA environment, his estimated noise exposure is reduced to 80 dBA.