June 22, 2012
Exposure To Traffic Noise Leads To Higher Heart Attack Risk
According to a study published in the journal PLoS ONE, exposure to traffic noise could lead to a higher risk of having a heart attack.
A new study shows a clear relationship between traffic noise and heart attack risk, with a 12 percent higher risk per 10 decibels of noise.
Previous work investigated whether combined effects of noise and air pollution caused by traffic could increase the risk of having a heart attack. However, those results were inconsistent.
The new study, which was led by Mette Sorensen on the Danish Cancer Society, was based on 50,614 participants.
"Previously, there seemed to be no effect up to around 60 decibels," Sorensen told Carrie Gann of ABC News. "But I see increases at around 40 decibels up to the highest level, around 82 decibels. It doesn't seem to be a level where there are no effects."
The scientists looked at people between 50 and 64 years of age in two of Denmark's largest cities, Copenhagen and Aarhus.
The team calculated how much noise each person had been exposed to, according to locations of their homes and an analysis of traffic patterns.
They found that 1,600 of the people in the study had their first heart attack during the decade of the research.
"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 the Northwestern Feinberg School of Medicine, told Gann.
Dr. Chip Lavie, medical director of cardiac rehabilitation and prevention at the Ochsner Medical Center in New Orleans, told Gann that earthquakes, as well as traumatic events like Hurricane Katrina, have been known to be consistent with a rise in the risk of having a heart attack, so "one could theorize is also in play during heavy traffic, with or without traffic noise."
The researchers speculated that all noise might prevent people from getting adequate sleep, which is a known risk factor for heart attacks.
Cardiologists say that where there are high volumes of traffic, air pollution is likely to increase as well, which could play a role in the increased risk.
The team took this into consideration in the new study, researching how much air pollution the study participants experienced. However, Sorensen said those results will be published in a separate study.
Those who were more at risk for a heart attack were also at a greater risk due to other factors as well, including: smoking, being less physically active, and having a poor diet.
Dr. David Frid, a cardiologist at the Cleveland Clinic, told ABC News it´s hard to discount how other cardiovascular risks may have played factor in the study participants who suffered from a heart attack.
"Cardiovascular disease is a complex process and there are multiple factors that could lead to a heart attack," Frid told the news agency. "As we identify these various factors, we have to then be cognizant of what we can do to ultimately reduce our risk of developing heart disease."
While previous studies have shown that the risk of having a heart attack while living by traffic increased at noise levels above 60 decibels, this study shows the risk increased between 40 and 80 decibels.
Sally Lusk of the University of Michigan, told Susan E. Matthews of MSNBC/My Health Day News that 10 decibels of noise is enough to interrupt a conversation, while 85 decibels is the minimum level at which hearing protection is required in a workplace.