Whether you’re stuck in it or breathing in the fumes, traffic is no good for your health. Now, a new study from Denmark finds that there’s something else about roadway traffic that’s bad for you: the noise. Researchers found that people who lived with louder sounds of traffic near their homes had a higher risk of heart attack.
For every 10-decibel increase in traffic noise, there was 12% higher risk of heart attack, according to the study by researchers at the Danish Cancer Society. The researchers said they started seeing increases in risk starting at around 40 dB.
Lead author Mette Sorensen and her fellow researchers followed more than 50,000 men and women ages 50 to 64 living in Copenhagen and Aarhus, two of Denmark’s largest cities. Each participant reported their lifestyle behaviors like diet and physical activity, as well as each place they lived over a 10-year period. The researchers monitored the participants’ health over the course of the study, comparing it to the geographic location of their homes. Researchers also figured out how much traffic noise each person had been exposed to by analyzing traffic patterns around the participants’ homes.
During the 10-year study, 1,600 people had a first attack and their risk was greater the louder the traffic noise near their home. The link between noise and heart attacks held even after the researchers accounted for other factors like air pollution exposure, diet, gender and weight.
There a variety of things that could explain the association: stress, for one. People who live in hectic, urban centers tend to have more stress than those in quieter locales, and stress is a well-known trigger of heart attack. “The noise itself probably does increase stress and the levels of stress hormones like adrenaline. Your blood pressure is probably going up as well,” Dr. Robert Bonow, a professor of medicine at Northwestern Feinberg School of Medicine, told ABC News.
Traffic noise may also prevent people from getting adequate sleep at night, another risk factor associated with heart attacks. What’s particularly insidious about a noisy environment is that people may not even know they’re being affected by it. “You might wake up thinking that you had a quiet night, but when you look at it in a lab, you see that your sleep stages have been disturbed,” Sorensen told My Health News Daily.
The study suggests that traffic noise doesn’t have to be deafening to affect your health. Forty decibels is about as loud as a bird call or the inside of a library; by comparison, a vacuum cleaner is 70 dB, and a passenger car traveling at 65 miles per hour measures 77 dB from 25 feet away.
If you live in a noisy area, Sorensen recommends sleeping in a quieter, interior room. The study was published in the journal PLoS ONE.