This photo by Chuck Kardous (NIOSH) is in the public domain
by Daniel Fink, MD, Chair, The Quiet Coalition
The title of this blog post is also the title of my latest publication. As I have often told my noise colleagues when they have tried to get me to write something about occupational noise exposure, I am not interested in occupational noise. I am aware that occupational noise exposure recommendations and standards in the U.S. and worldwide are set too high and do not protect workers from hearing loss, but at least workers have noise exposure recommendations and standards and in this country a workers comp system to compensate them if they suffer occupational noise-induced hearing loss. The general public has no such protections.
Why did I present a paper on occupational noise at the 183rd meeting of the Acoustical Society of America in Nashville last December, and write that presentation up as a manuscript now published in the ASA’s journal, Proceedings of Meetings on Acoustics? Because as Table 1 of my paper shows, the National Institute for Occupational Safety and Health recommended exposure limit (REL) of 85 A-weighted decibels* (dbA) appears to form the basis for much of the available noise exposure guidance for the public, even though NIOSH states that its recommended exposure limit is not a noise exposure recommendation for the public. The only evidence-based safe noise exposure level to prevent hearing loss is the EPA’s 70 decibels for 24 hours.
Why does the NIOSH REL need to be revised downwards? There are three main reasons. First, as the NIOSH blog post notes, NIOSH assumed workers had quiet when not at work, something research now shows is no longer true. Therefore, occupational noise exposure must be reduced to prevent occupational hearing loss, which is caused by cumulative noise exposure.
Second, occupational studies correlating noise exposure with hearing loss only considered 40-year work lives, but with people in industrial nations living near or longer than 80 years–at least before the COVID pandemic–lifetime noise exposure must be considered. These days noise exposure begins in childhood, continues outside the workplace during working years, and extends for one’s entire life.
Third, the occupational studies correlating noise exposure with hearing loss, most done before the 1970s, used only limited pure-tone audiometry to detect hearing loss. More sensitive tests of auditory damage, e.g. questions about tinnitus (ringing in the ears) and hyperacusis (sensitivity to noise that doesn’t bother others), extended frequency audiometry, speech-in-noise testing, and other research techniques are likely to find auditory damage much earlier in many more people. For example, a study by Liberman et al. found extensive auditory damage in relatively young music students who had normal screening audiograms.
I hope my latest publication will lead to evidence-based revision of occupational noise exposure recommendations and standards, with subsequent downward revision of noise exposure guidance for the public.
A quieter world will be a safer, healthier, and better world for all.
*A-weighting adjusts sound measurements to approximate the frequencies heard in human speech. A-weighting is used in occupational noise recommendations and standards because the compensable injury when noise-induced hearing loss occurs is the inability to understand speech.
