Health
Car horns, sirens and other traffic noise increase the risk of stroke, especially in older adults, according to a new study.
More than 51,000 people from Denmark took part in the studies, which were planned to find a link between traffic noise and strokes. It was found that every 10 decibels of noise increases the risk of stroke by 14 percent. For people over 65, such noise increases risks by 27 percent.
The biggest risks are when the noise exceeds 60 decibels, which is more than the volume of a normal conversation, the researchers said. A decibel is a logarithmic unit, so 60 decibels noise is 10 times louder than 50 decibels.
Previous studies have linked traffic noise to increased risks of heart attacks and high blood pressure, however, a new study has found that this noise can also lead to to a stroke.
Scientists made their findings after taking into account other factors that contribute to stroke, including age, gender, smoking, physical activity, vegetable consumption, and the impact of train and airport noise, as well as the effect of dirty air.
It is necessary to reduce traffic noise, according to researcher Mette Sørensen from the Institute of Cancer Epidemiology in Copenhagen. However, she also noted that research results only show an association, and do not indicate that noise is a direct cause of stroke. Further research is needed to explore this link more deeply.
Noise pollution
Mete and her colleagues analyzed data from Danish citizens living in Copenhagen and Aarhus who completed questionnaires between 1993 and 1997. At the same time, scientists also checked the participants' medical records and their places of residence. Traffic noise was assessed using models that took into account a combination of traffic, speed, road conditions and distance from home to road.
Approximately 35 per cent of participants were exposed to noise levels greater than 35 decibels. The noise level that could presumably influence the link with stroke was estimated to be between 40 and 80 decibels. As a result, it turned out that 1,881 study participants had a stroke.
Scientists estimate that traffic noise may be associated with 8 percent of all strokes and 19 percent of cases when people are over 65 years old.
Why does noise increase stroke risks?
It is believed that exposure to noise increases blood pressure and causes changes in stress hormone levels, which in turn can increase the risk of stroke. In addition, exposure to traffic noise can also lead to sleep disorders, which subsequently increases the risk of stroke. Older people are most sensitive to sleep disorders, which explains why the problem affects people over 65 years of age more.