Noises off (a study in hearing protection)

Forgive the theater reference. I was reading a study from the University of Washington about noise exposure and found something interesting.  It stated that sheet metal workers were wearing hearing protection around 90% of the time when noise levels were above 85 dBA (OSHA’s standard for maximum exposure) when maintaining and fabrication metal products.

So they wear hearing protection when they are working? That makes sense, right? Don’t get me wrong: 90% compliance is great. But what I found interesting was how much that number dropped when workers were doing everything else.

Take a look at this chart, showing the noise levels and compliance rates for the other activities going on around the workers:

Tasks Average noise level (dBA) Maximum noise level (dBA) % time hearing protection worn
Break, Rest, Lunch, Cleanup 81.0 100.0 7%
Operation Work Vehicle 82.6 105.3 0%
“Other” Tasks 83.6 103.7 66%
Maintaining Metal Products 86.1 114.0 86%
Fabricating Metal Products 87.8 113.2 93%
Installing Metal Products 88.2 111.5 21%
Manual Material Handling 90.2 108.4 83%

They had more exposure from activities going on around them than they did from their own work.

Average noise levels when fabricating and maintaining is about 87 dBA. Noise levels for everything else was about 85.1 dBA. This is just slightly above the maximum threshold, but still over. During this time, hearing protection use drops to 35% of the time.

So while an employee may wear hearing protection when performing their own work, they may be at a higher risk of hearing damage from everyone else’s work.

Here is what study recommended:

“Educational programs can help make sheet metal workers aware that some activities on the job site have potentially hazardous noise levels. Sheet metal workers in the construction industry should be enrolled in a hearing conservation program, and efforts should be made to reduce the noise levels of construction activities and to increase the use of hearing protection.

All hearing protectors are labeled with a Noise Reduction Rating (NRR), a laboratory estimate of how much noise the hearing protector will block. Typically, the NRR level is about two times higher than the protection most workers experience in actual use.

Almost all full-shift noise exposure measurements on sheet metal workers were below 87 dBA. To adequately protect against these average noise levels, we recommend hearing protectors with an NRR of 12 dB. For most activities, an NRR higher than this will interfere with normal communication and work.

Workers who find that hearing protectors with a very high NRR (33 dB is the highest available) make it difficult to hear regular work sounds should try a different hearing protector with a lower NRR. On the other hand, workers exposed to very high levels of noise should use a hearing protector with a higher NRR. Workers exposed to intermittent noises should consider using earmuffs or banded earplugs, which can be re­moved and inserted quickly.

A single type of hearing protector will not work for all workers and all exposure levels, so it is important to have several types and styles of hearing protectors available.”

Now, it’s your turn

What are you finding to be the best way to protect your employees’ hearing? And how do you promote compliance to hearing protection standards?

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