January 26, 2011

Link Between Stroke And Traffic Noise Discovered

Noisy traffic can actually increase a person's risk of stroke, according to a new study published Wednesday in the European Heart Journal.

In a study of more than 51,000 people, Dr. Mette Sørensen, senior researcher at the Institute of Cancer Epidemiology, Danish Cancer Society in Copenhagen, Denmark, and colleagues discovered that the risk of having a stroke increased 14% for every 10 decibels of traffic-related noise.

Furthermore, in those over the age of 65, every 10 decibels increased stroke risk by 27%, up to a total of 60 additional decibels. Above that threshold, the researchers discovered that the chance of stroke spiked even more.

According to AFP, a typical busy street produces between 70 and 80 decibels of noise.

"Our study shows that exposure to road traffic noise seems to increase the risk of stroke," Sørensen said in a statement Tuesday. "Previous studies have linked traffic noise with raised blood pressure and heart attacks, and our study adds to the accumulating evidence that traffic noise may cause a range of cardiovascular diseases."

"These studies highlight the need for action to reduce people's exposure to noise," she added, calling this "the first study ever to investigate the association between exposure to road traffic noise and risk of stroke" and noting that "more research is needed before any firm conclusions can be made."

The researchers report that they took into account other factors that could have influenced the results, such as air pollution, smoking, diet, alcohol consumption, and exposure to noise from trains or aircraft. Furthermore, they are quick to point out that their findings do not show that traffic noise causes stroke--only that there is a correlation between the two.

"If we assume that our findings represent the true risk, and the association between traffic noise and stroke is causal, then an estimated eight percent of all stroke cases, and 19% of cases in those aged over 65, could be attributed to road traffic noise," Sørensen said.

"The population in this study, however, lived mainly in urban areas and is, therefore, not representative of the whole population in terms of exposure to road traffic noise," she added. "However, if we take the exposure distribution of all dwellings in Denmark into account, we find that about 600 new cases of stroke could be attributed to road traffic noise in Denmark each year. There are 5.5 million inhabitants in Denmark and a total of 12,400 new cases of stroke each year."


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