We’ve all heard about the silent killers—health hazards such as stress and hypertension that can wield their dangerous effects by sneaking up on us, without our realizing it. But scientists are also finding that a lifetime of everyday noise levels can be just as dangerous, not just to our hearing health, but to our stress levels, sleeping ability, and cardiovascular health.
The noise levels we’re talking about extend beyond those we’re already well aware of—those produced by excessively loud gadgets or machinery that are damaging to structures in our inner ear. For years, most hearing experts have accepted 85 decibels (dB) as a line not to be crossed without hearing protection. This limit was originally set by the National Institute for Occupational Safety and Health when it ruled that a worker shouldn’t be exposed to 85 dB in an eight-hour workday without suitable protection in the form of earplugs or ear muffs, among other criteria. Because every 3-dB increase is twice as loud as the former level, the permissible amount of time spent on the job without hearing protection, according to NIOSH, is halved to four hours at 88 dB, halved again to two hours at 91 dB, and so on.
But those are work exposures. What about the times in your day when you’re around noise levels that don’t hit the magic number of 85, but still can be potentially harmful? What about the din of a dinner party or the racket of city traffic?
Scores of studies have linked cardiovascular disease, sleep disorders, and hypertension with too-high decibel levels, which can be much lower than 85 dB. In 1974, the Environmental Protection Agency established noise-exposure limits for the health and welfare of the American public. Their suggested exposure limit to protect against hearing loss was 70 dB on average over a 24-hour period and their suggested noise limit for general welfare (e.g., lack of annoyance or interference with activities such as sleeping, conversing, or working) was 55 dB outdoors and 45 dB indoors, also averaged over 24 hours. Our world today is often far noisier than those numbers—a walk down the street in New York City can expose a person to 73.4 dB, on average, mostly from the traffic noise—and some researchers contend that a steady dose of noise from 50 dB up can damage our cardiovascular health.
According to a small study recently published in Sleep Medicine, researchers in Taiwan found that hospital cafeteria workers who were exposed to higher noise levels (on average, 76.8 dB compared to 61 dB) for eight hours were more likely to experience lower-quality sleep at night as well as to exhibit higher blood pressure levels and an increase in the stress hormone cortisol.
In addition, in a 2015 economic analysis published in the American Journal of Preventive Medicine, researchers found that a 5-dB decrease in noise exposure across the U.S. population could potentially reduce the number of people with hypertension by 1.4 percent, and those with coronary heart disease by 1.8 percent. In terms of reduced cases, that’s 1.2 million and 279,000 fewer cases, respectively. What’s more, a whopping $3.9 billion could be saved annually through reduced healthcare costs and improved productivity—again, by merely turning down the volume by 5 dB.
Noise today is being likened to what secondhand smoke once was (read this article from the January 2017 issue of the American Journal of Public Health and this recent article in the Washington Post) because of its pervasiveness in our environment and because we’re often subjected to dangerous levels involuntarily. Just as smoke-free zones in public areas have become commonplace, wouldn’t it be wonderful if the same could be accomplished in reducing everyone’s exposure to noise?
Two free apps that can help you address noise in your environment are:
- iHEARu – a crowdsourced app that allows users to share information about the noise levels of business establishments in your area, and
- NIOSH sound level meter – an app that helps you measure noise levels in your workplace.