Salon had an article about noise pollution a few months ago that is worth reading (free access after watching a short advertisement). Here's an excerpt about health effects of noise pollution (my emphasis):
But you don't have to be an anti-noise crusader to suffer physical effects from noise, even if you're sleeping right through it. Scientists at Imperial College London monitored the blood pressure of 140 sleeping volunteers who lived near London's Heathrow airport. They discovered that subjects' blood pressure rose when a plane few overhead even when the subjects remained asleep. A study of 5,000 45-to-70-year-olds living near airports for at least five years found that they were at greater risk of suffering from hypertension, aka high blood pressure, than their counterparts in quieter realms. People with high blood pressure have an increased risk of developing heart disease, stroke, kidney disease and dementia. In 2007, WHO estimated that long-term exposure to traffic noise may account for 3 percent of deaths from ischemic heart disease among Europeans.
Think about that bold-faced part for a second: "subjects' blood pressure rose when a plane few overhead even when the subjects remained asleep." In other words, you can't escape noise pollution by sleeping. Based on my rudimentary understanding of human evolution, I'd guess that noises disturb our sleep as part of our innate 'fight or flight' response — the brain never quite turns off, it's always listening for threats to our safety.
A few months ago, 60 Minutes had a fascinating 2-part story about the science of sleep. One of the experiments they featured involved a human subject spending a night in their laboratory. After the subject fell asleep (perhaps they even waited until he or she reached the REM sleep state), they did one of two things: 1) periodically sounded an alarm at a volume that wouldn't wake the subject or 2) let the subject sleep undisturbed through the night. The next morning they performed some tests to determine the quality of the sleep — they found that sleep quality was far lower when alarms were activated during sleep. Again, even in sleep you can't escape noise pollution. This makes me wonder how much of our society's productivity is lost because of reductions in sleep quality by all-night train horns, sirens, loud motorcycles, car alarms, and other noise.
The Salon article continues with more details about the harm of noise pollution:
Not only can too much loud noise damage your hearing, or disrupt your sleep, it can literally suck the life out of you thanks to the human body's fight-or-flight response. "The human auditory system is designed to serve as a means of warning against dangers in the environment," explains Louis Hagler, a retired internal medicine specialist in Oakland, Calif. "Noise above a certain level is perceived by the nervous system as a threat." The body responds to that threat with an outpouring of epinephrine and cortisol, the so-called stress hormones. "Your blood pressure goes up, your pulse rate goes up, there is a sudden outpouring of sugar into the bloodstream so the body is prepared to meet whatever threat there is in the environment."I'll end with a rant about one of my noise pet peeves: car alarms that beep or chirp whenever they are turned on or off (i.e., when the car is locked or unlocked). I hope there is a special circle of hell reserved for the engineers who designed -- and the managers who approved -- this feature. On my car, the original factory setting was for the horn to sound when the alarm was activated (by locking the doors with a key or the remote). Fortunately, it was possible to turn off the honking, and now when I lock the doors the lights flash and a red light near the driver's side rear-view mirror starts blinking. In my opinion, visual feedback is the right way to do it, because if you can't tell that lights flash when you lock your car, you shouldn't be driving! (If your car beeps or honks when you lock or unlock, please consider deactivating that 'feature' the next time you take it for service.)
If exposures are intermittent or rare, the body has the chance to return to normal. But if the exposure is unrelenting, the body doesn't have a chance to calm down, and blood pressure and heart rate may remain elevated, Hagler explains. That's why what seems like a mere annoyance can actually have long-term health effects. "There is no question that people who live near a busy roadway are experiencing effects on their blood pressure," says Hagler.
As Bean attests, once you tune into the din, it's hard to tune out again. "It's like an allergy -- once you get sensitized to one of these things then they all bother you, and then each one builds on the other," he says. And what's a mere nuisance to one person is another's bête noire. "There is no evidence that noise causes mental illness itself, but there is little doubt that it may accelerate or intensify some kind of mental disorders," explains Hagler. He adds that symptoms of exposure to noise pollution include anxiety, nervousness, nausea, headaches, emotional instability, argumentativeness and changes in mood. No wonder excessive noise has been used as a form of torture.
(For more information and resources about noise pollution, check out the Noise Pollution Clearinghouse.)
Drawing of ear anatomy from the book "Tidens naturlære" 1903 by Poul la Cour, downloaded from Wikimedia Commons.
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