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Study Shows Road Traffic Noise may Increase Stroke Risk

A new study published in, “The European Heart Journal”, on January 27, 2011, indicates that exposure to the noise of road traffic can actually increase the risk of stroke, especially in people age 65 and above.

This study is among the first of its kind that investigates the link between traffic noise and the risk of stroke has found that for each 10 decibels of extra noise, the risk of stroke is increased by up to 14% in the age 65 and over category of the more than 51,000 participants of the Danish study. Those under 65 showed no significant increased risk of stroke. The over 65 range of participants showed that over 60 decibels of road noise was the average threshold limit. Going above that level increased the risk even further. These are some startling figures, indeed.

The study, which is one among the first to investigate the links between road traffic noise and the risk of stroke, found that for every 10 decibels more noise the risk of having a stroke increased by 14% among the 51,485 study participants.

When the Danish researchers began looking at the data more closely, they found that for people aged less than 65 years there was no statistically significant increased risk of stroke; however, the risk increased by 27% for every 10dB of higher road traffic noise in those aged 65 years and over. Furthermore, in the older people they found indications of a threshold limit at approximately 60 dB, above which the risk for stroke seemed to increase even more.

Senior researcher and leader of the study at the, “Institute of Cancer Epidemiology, Danish Cancer Society” in Copenhagen, Denmark, Dr. Mette Sørensen, said that: “Our study shows that exposure to road traffic noise seems to increase the risk of stroke. 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.”

“This is the first study ever to investigate the association between exposure to road traffic noise and risk of stroke, and, therefore, more research is needed before any firm conclusions can be made.”

Of course, the study was based on the Danish, “Diet, Cancer and Health Study” and included people ages 50 through 64. The average follow up time was about 10 years and in that time, more than 1,881 of the 51,485 participants had suffered a stroke.

While the study included the consideration of many other factors, such as air pollution, smoking, diet, alcohol, caffeine, airplane noise and railroad noise, placement and position including height above the roads or railroads where the participants homes were located; it also included a noise mapping program that has been used in Scandinavia for a number of years.

Up to 72% of the participants lived at the same address for the duration of the study. The lowest estimate for noise exposure was about 40 decibels while the highest was 82 decibels.

Dr. Sorensen estimates that if their calculations and results are true findings that the risk of stroke is causal. That an estimated 8% of all stroke cases and up to 19% in people over age 65 could be linked to exposure to road and traffic noise.

While the participants of this study lived mainly in some rural areas; these findings do not necessarily present 100% accuracy in the findings, but it does indicate that there is increased stroke risk due to the noise and may indicate that other studies could show that many cardiovascular problems are linked, as well, especially in larger cities where the the level of traffic and road noise is much greater.

This study definitely shows that noise does, in fact, act as a stressor, disrupting sleep which can lead to hypertension or high blood pressure, can increase the heart rate and level of stress hormones and may even lead to heart disease and attacks.

Older persons have been found to have more problems with sleep and are more susceptible to various sleep disturbances, thus resulting in a greater risk of stroke for those over 65.

While other studies have also determined a link, further studies must be done to determine exactly how road traffic noise can lead to hypertension and heart problems like stroke, but these findings at least show that there is, definitely a link.