- Traffic, including car, train and airplane
- Factory or other industrial settings
- Outdoor construction
Prolonged Noise Can Increase Stress Hormones
A study published in the British Medical Bulletin found that "noise interferes in complex task performance, modifies social behavior and causes annoyance." In some cases, annoyance may lead to stress, which can lower the body’s resistance to illness and disease. The study also found that occupational and environmental noise exposure may be associated with high blood pressure as well as elevated levels of stress hormones, called catecholamines, that are secreted by the adrenal glands.2 Catecholamines act much like cortisol, another adrenal hormone. They prepare the body for "fight or flight" by increasing blood pressure and heart rate and releasing glucose (sugar) into the body to be burned for energy. High catecholamines in the body can cause psychological stress and restrict blood flow to the heart and brain, increasing the risk of heart attack and stroke.3Noise Pollution and Cognitive Function
The British Medical Bulletin article also reported that noise exposure may also slow rehearsal in memory, adversely affect memory selectivity and executive functioning/task performance. A study published in the European Heart Journal raised similar concerns. The authors found that nighttime noise can cause sleep disturbances, which can perpetuate high blood pressure and stress responses.4 Nighttime noise can also contribute to oxidative stress (free radical damage) and chronic inflammation, which is the starting point for a wide range of illnesses. Not only that, but – as we’ve noted many times in these pages -- chronic poor sleep also contributes to cognitive decline and Alzheimer’s disease.5How Loud is Too Loud?
Sound is measured in decibels (dB). Roughly 76 dB is the threshold for what’s considered loud or annoying, although "annoying" can vary from one person to the next. The average human pain threshold is about 110 dB. To give you an idea of what that means. . .- 50 feet from the freeway during rush-hour traffic is 76 dB
- A passenger car traveling at 65 mph, 25 feet away is 77 dB
- A diesel truck going 40 mph at 50 feet is 84 dB
- A propeller plane flying overhead at 1,000 ft is 88 dB
- A power mower is 96 dB
- A Boeing 737 or DC-9 aircraft at 6,080 ft before landing is 97 dB
- Live rock music is between 108-114 dB(6)
How You Can Protect Yourself
The evidence shows that noise pollution doesn’t directly cause cognitive decline and Alzheimer’s disease, but it does increase a number of risk factors for the condition, such as stress, blood pressure and quality of sleep. Not to mention the fact that hearing loss itself can contribute to Alzheimer’s disease and cognitive decline. (See Issue #261 for more information about the effects of hearing loss on cognition.) If you find yourself asking people to repeat things, or you turn the TV up to a volume that drives everyone else out of the room, you need to get your hearing checked. Hopefully your hearing is still fine. Even so, if you live or work in a noisy environment and have the means to change home or job, you may want to consider doing so. If you’re unable to move out of noisy environments, you may be able to fend off some of the effects of noise by spending time in quiet places whenever possible. Consider earplugs, especially at night. I don’t know how people can stand to live near airports. My heart goes out to them. Research shows that spending time in quiet green spaces, whether it’s a city park or a rural setting outside the city, can reduce cortisol levels, lower blood pressure, reduce heart rate and generally provide stress relief a doctor can measure.6 A person’s blood pressure can plummet just by spending 20 minutes in such a place.- Noise pollution.
- Noise pollution: Non-auditory effects on health.
- Catecholamines and environmental stress.
- Cardiovascular effects of environmental noise exposure.
- Impact of sleep on the risk of cognitive decline and dementia.
- Comparative examples of noise levels.
- Acute effects of visits to urban green environments on cardiovascular physiology in women: A field experiment.
