Why we must lower the occupational noise exposure limit

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by Daniel Fink, MD, Chair, The Quiet Coalition

Kat Sezter, editorial associate at the Acoustical Society of America, asked that we help publicize the ASA’s latest podcast, and I’m glad to do that. I’m especially glad because it’s my first time on a podcast, based on an article I wrote after speaking on this topic at the December 2022 ASA meeting in Nashville, Tennessee.

As I wrote in the article, the National Institute for Occupational Safety and Health recommended exposure limit (REL) of 85 A-weighted decibels (dBA*) needs to be revised downwards for four reasons:

  1. NIOSH assumed workers have quiet when not at work, something that is no longer true.
  2. More sensitive measures of auditory damage than limited-frequency pure tone audiometry used by NIOSH would find earlier and more prevalent noise-induced auditory damage.
  3. Lifetime noise exposure must be considered, not just 40-year occupational noise exposure.
  4. NIOSH considered up to a 15 decibel hearing loss as normal, when normal hearing really doesn’t have any measurable hearing loss.

As I confess in the podcast, I’m not really interested in occupational noise issues. Why not? Because workers have the NIOSH REL, the Occupational Safety and Health Administration permissible exposure levels for noise and the workers compensation system to pay for hearing health care if they suffer hearing loss. My interest is the public, which has only the tort law system to turn to if we develop hearing loss, tinnitus or hyperacusis after going to a loud rock concert or sports event.

The public isn’t exposed to 85 dBA noise for eight hours a day, five days a week, 50 weeks a year for 40 years. So, why does the NIOSH REL matter? Because 85 dB or dBA is often incorrectly cited as a safe noise exposure level for the public, or the level at which auditory damage begins. These articles in Forbes and U.S.News and World Report from December 2023 are just two examples.

As I discuss at the end of the podcast, it’s human nature to want more. And most Americans don’t understand that the decibel scale is logarithmic. As with posted speed limits or recommendations for calories, salt or alcohol intake, people seem to think that just a little more can’t hurt. So they think that if 85 dB or dBA is safe, 100 dB won’t really hurt. But OSHA recommends only 15 minutes of noise exposure at 85 dBA to prevent occupational hearing loss, using NIOSH’s current but obsolete research.

Even if audiologists continue to cite the NIOSH REL as safe for the public, the REL should be recalculated downward to protect everyone’s hearing. And, a quieter world will be a better and healthier world for all.

*A-weighting adjusts unweighted sound pressure measurements for the frequencies heard in human speech. A-weighting is used in occupational health because the inability to understand speech is the compensable workplace injury.

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