Lately, we've had a lot of customers rent our area sound level and personal noise exposure instruments to help design and implement their hearing protection programs. By knowing the source of loud ambient noise or measure workers' day-long exposure to noise, they can determine where workers need to be using hearing protection gear, like noise-cancelling headphones or ear plugs.
The other day, a customer asked me this: When I'm doing an 8-hour time-weighted average study, what do I tell the workers to do during lunch? Do they turn the noise monitors off? Do I collect them?
It's a great question, and the answer is, of course: It depends.
But let me explain what I mean by that...
In the OSHA Technical Manual (Section III, Chapter 5: Noise) Appendix H, there's a checklist for conducting a noise inspection.
For full-shift sampling, it suggests this:
Tell the worker that you will check back regularly and to let you know right away if there is a problem with the unit or with wearing it. Instruct the worker being sampled not to remove the dosimeter unless absolutely necessary, and not to cover the microphone with a coat or outer garment or move the microphone from its installed position. Let the worker know when the dosimeter will be removed. For example, explain to the worker that you will be collecting the noise dosimeters prior to lunch, and then after lunch, you will resume sampling them.
If workers eat lunch or take breaks in their work area, and continue to be exposed to the noise, you should consider leaving the dosimeter on during lunch, as it will affect the results of the study.
So, what OSHA recommends is that if a worker takes lunch or breaks in a noisy work area, the dosimeter should be left on, as it adds to the cumulative noise exposure. But if the worker takes breaks or lunch in a quiet area, it's not necessary to keep the dosimeter running.
To see the full section and chapter, you can read it in HTML or download the section in PDF: https://www.osha.gov/dts/osta/otm/new_noise/
A complete workplace noise exposure and sound level survey includes using both area noise monitors, to detect noisy locations or spikes in ambient sound level, and using personal noise dosimeters, to monitor the cumulative noises a worker encounters over the course of a full day. You can see our complete line of sound level and noise monitors available to rent.
Now, it's your turn...
Do you have a policy in place for running dosimeters during lunch during 8-hour TWA studies? Do you have the workers leave them on and running? Have you seen any noticeable skewed results from running your tests that way?