In a suburban neighborhood curbside on a cloudy day, a jet plane roars overhead. A noise recorder registers a decibel reading ranging from 59 to 94. Then it becomes quiet. But again about every three minutes, a jet blazes overhead with an ear-piercing roar. A growing body of research shows that this kind of chronic noise — which can rattle a neighborhood over 280 times a day, more than 105,000 each year — is not just annoying. It is a largely unrecognized health threat that is increasing the risk of hypertension, stroke and heart attacks worldwide, including for more than 100 million Americans. We’ve all been told to limit the volume on our headphones to protect our hearing. But it is the relentless din of daily life in some places that can also have lasting effects. Anyone who lives in a noisy environment, like the neighborhoods near a major highway, may feel they have adapted to the cacophony. But data show the opposite: Prior noise exposure primes the body to overreact, amplifying the negative effects. Even people who live in relatively peaceful rural and suburban communities can be at risk. The sudden blare of trains that run periodically can be especially jarring to the body because there is little ambient noise to drown out the jolt. A siren shrills. A dog barks. Engines run. Jackhammers clack. Unpleasant noise enters your body through your ears, but it is relayed to the stress detection center in your brain. This area, called the amygdala, triggers a cascade of reactions in your body. If the amygdala is chronically over-activated by noise, the reactions begin to produce harmful effects. The endocrine system can overreact, causing too much cortisol, adrenaline and other chemicals to course through the body. A handful of glandular system regions throughout the body may be involved, such as the thyroid gland in the neck and the pancreas in the torso. The sympathetic (involuntary) nervous system can also become hyper-activated, quickening the heart rate, raising blood pressure, and triggering the production of inflammatory cells. Over time, these changes can lead to inflammation, hypertension and plaque buildup in arteries, increasing the risk of heart disease, heart attacks and stroke. To understand this pathway, researchers scanned the brains of people as they listened to unpleasant sounds and watched live as their amygdalas activated. They monitored blood pressures and noise intensity subjected to auto assembly plant workers during a shift to see their blood pressures and heart rates rise with their noise exposure.

To simulate relentless nights, scientists played dozens of sporadic recordings of passing trains and planes overhead in healthy volunteers’ bedrooms — recordings taken of real disruptions from people’s homes. They found that the next morning, the volunteers had higher adrenaline levels, stiffened arteries, and spikes in plasma proteins that indicate inflammation.

When researchers analyzed the brain scans and health records of hundreds of people at Massachusetts General Hospital, they made a stunning discovery: Those who lived in areas with high levels of transportation noise were more likely to have highly activated amygdalas, arterial inflammation and — within five years — major cardiac events.

The associations remained even after researchers adjusted for other environmental and behavioral factors that could contribute to poor cardiac health, like air pollution, socioeconomic factors, and smoking. In fact, noise may trigger immediate heart attacks: Higher levels of aircraft noise exposure in the two hours preceding nighttime deaths have been tied to heart-related mortality.


Sound is often measured on a scale of decibels, or dB, in which near total silence is zero dB and a firecracker exploding within a meter of the listener is about 140 dB. When a professional sound level meter was used to record the decibel levels of common sounds and environments, some examples follow:

A chart showing decibel measurements for a quiet room at 27 dB, a busy street at 69 dB, a hair dryer at 87 dB and a freight train at 117 dB. But the difference in how loud the train sounds to the ear is much more dramatic: The train sounds more than 500 times as noisy. When we compare the relative loudness of three sounds with a quiet room, a busy street is 19 times as loud, a hair dryer is 66 times as loud, and a freight train is 516 times as loud. That’s because the decibel scale is logarithmic, not linear: With every 10 dB increase, the sense of loudness to the ear generally doubles. And that means regular exposure to even a few more decibels of noise above moderate levels can trigger reactions that are harmful to health.

According to the World Health Organization, average road traffic noise above 53 dB or average aircraft noise exposure above about 45 dB are associated with adverse health effects. Nearly a third of the U.S. population lives in areas exposed to noise levels of at least 45 dB, according to a preliminary analysis based on models of road, rail and aircraft noise in 2020 from the Department of Transportation. Approximately 3 million people in the U.S. live in areas with average outside noise levels above 70 dB

The relative number of people in the United States estimated to live at each of five different noise levels estimated as the following: Three million people may live in areas above an average of 70 dB; nine million in areas from 60 to 70 dB, 39 million from 50 to 60 dB; 44 million from 45 to 50 dB; and 232 million in areas below 45 dB.

The nighttime noise that a person in such an environment experiences is considered particularly detrimental to health because it can fragment sleep and trigger a stress response, even if the person does not recall being roused. The W.H.O. has long recommended less than 40 dB as an annual average of nighttime noise outside bedrooms to prevent negative health effects, and less than 30 dB of nighttime noise inside bedrooms for high-quality sleep. That’s even quieter than inside this house when a train isn’t going by. Mounting research suggests that the relationship between noise levels and disease is eerily consistent: A study following more than four million people for more than a decade, disclosed that, starting at just 35 dB, the risk of dying from cardiovascular disease increased by 2.9 percent for every 10 dB increase in exposure to road traffic noise. The increase in risk of dying from a heart attack was even more pronounced: Also starting at just 35 dB, it increased by 4.3 percent for every 10 dB increase in road traffic noise.

Scientists believe that pronounced fluctuations in noise levels might compound the effects on the body. They suspect jarring sounds such as recurring jet engines, a pulsating leaf blower, or the brassy whistle of trains are more detrimental to health than the continuous whirring of a busy roadway, even if the average decibel levels are comparable. In a subsequent Swiss study, higher degrees of nighttime “noise intermittency” — or the extent to which sound events were distinguishable from the background levels — were associated with heart disease, heart attacks, heart failure and strokes.


As with so many health issues, poor people and communities of color are more likely to experience excessive noise exposure because they often have fewer housing choices and are more likely to live near high-traffic roads, raucous waste dumps and industrial areas. According to a study of more than 94,000 schools, students in those estimated to be most highly exposed to road or aviation noise, were Hispanic, Black, or Asian/Pacific Islander. Such excess noise in schools is associated with heightened stress hormones, lower reading scores and even hyperactivity.

Nighttime noise shows similar inequities. Census data show that city communities with almost no low-income residents average 44 dB at night, compared with about 47 dB in those where half of residents fall below the poverty line. Neighborhoods with almost no Black residents averaged about 42 dB at night, compared with about 46 dB in communities that were predominately Black. The difference of a few dBs might not seem like much, but according to a analysis of more than 100,000 U.S. nurses, for every one dB increase, the risk of developing cardiovascular disease climbs by roughly one percentage point. And as dBs climb, so too do associations with death because of cardiovascular disease and heart attack.

The disparities in noise exposure are likely to be much larger than the noise model suggests, researchers said, since wealthier households and schools are more likely to install triple-pane windows and more insulation.


Fifty years ago, under the Noise Control Act of 1972, the newly formed Environmental Protection Agency was a trailblazer in recognizing the danger of noise and addressing it: It educated the public, established safety limits, published analyses on various factors, and recommended actions to mitigate harm. But its office of noise abatement was defunded by the Reagan administration, rendering policies unenforceable and regulatory criteria obsolete. The Occupational Safety and Health Administration’s eight-hour workplace noise limit is still 90 dB.

European countries have far outpaced the rest of the world in regulating noise. The European Union requires member nations to monitor and assess sound levels across regions and to produce new action plans every five years to address communities at greatest risk. The E.U. now mandates quiet brake locks on rail freight fleets and noise labels on outdoor power equipment; ialso requires noise reduction in car manufacturing and mitigation efforts at airports. Individual cities and countries have taken additional measures. Paris has installed noise cameras that measure the sound level of vehicles and fine drivers who exceed them. Berlin has used new bike lanes to reduce the flow of engine-powered vehicles and move the source of the noise to the center of the road, away from houses. Switzerland has introduced national “quiet hours” — overnight, one midday hour on weekdays, and all day on Sundays.

While scientists say it’s too soon to make a prediction about the effects of these policies on cardiovascular health, several European countries have reported tens of thousands fewer residents exposed to major sources of noise. Like many health issues, protection against noise would be economically advantageous. Economists who analyzed health care spending and productivity loss because of heart disease and hypertension, have argued that a 5 dB reduction in U.S. noise could result in an annual benefit of $3.9 billion. But unlike most other contributors to heart disease, noise cannot be addressed fully between a patient and a doctor. Protection requires changes in local, state and federal policy.


Beyond noise’s effects on general health, hearing loss is the third most common chronic health condition in the US. Almost twice as many people report hearing loss as report diabetes or cancer. Noise exposure away from one’s job can damage hearing just as much as working in a noisy place. Being around too much loud noise—like using a leaf blower or going to loud concerts—can cause permanent hearing loss. And once it’s gone, it won’t return! Moreover, hearing loss may occur before one notices its presence. Over time, listening to loud sounds at high dB levels can cause hearing loss—or other hearing problems like a ringing sounds in the ear that won’t go away. The louder a sound is, and the longer one is exposed to it, the more likely it will damage one’s hearing. Again, here are a few means to reduce noise exposure:

  • Avoid noisy places whenever possible.
  • Use earplugs, protective ear muffs, noise canceling headphones when near loud noises.
  • Keep the volume down when watching TV, listening to music, and using earbuds or headphones.

    Unfortunately, our modern living presents lots of noise pollution. We must, however, do our best to continue collecting data and, whenever possible, reduce noise production and our sensory exposure to the ubiquitous danger!



Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top