A new Danish study, published in the European Heart Journal has found a clear correlation between noise levels and stroke risk for seniors. The louder the noise, the higher the risk of stroke. In fact, the researchers reported that the overall risk of stroke rose by 14% for every 10 decibel rise in noise levels for all individuals in their study, and for those aged 65 or over the risk of stroke increased 27% for each 10 decibel rise in noise exposure.
The research report indicates that this was the first study to examine whether there is a link between stroke risk and traffic noise. The study included 51,485 individuals. Medical and residential histories (including level of exposure to traffic noise) were gathered on all 51,485 subjects, and they were followed for an average of ten years. During that ten year period 1,881 of the the subjects suffered a stroke.
In examining the data, researchers concluded that for individuals 65 and over, there was a 27% increase in risk of stroke for each 10 decibel rise in exposure to noise. However, for those under 65, there was no statistically significant increase in risk of stroke in relation to exposure to noise. And, they found that the risk of stroke among the elderly rose at an even higher rate when decibel levels were over 60.
Study leader, Dr Mette Sørensen, at the Institute of Cancer Epidemiology, Danish Cancer Society, was quoted as saying, “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.”
He explained, “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.”
The researchers explained that in their study they controlled for several factors which may otherwise have had the potential to distort their findings, including air pollution, aircraft and railway noise, smoking status, eating habits, and alcohol and caffeine consumption.
They determined exposure to noise levels by measuring noise levels of several different Scandinavian residential areas over a period of years. In doing so, they measured traffic speed, composition, road type, road surface, building polygons and where exactly people’s homes were in relation to the roads (height, position, etc.). The noise levels of the residential areas included in the study ranged from 40 decibels to 82 decibels. Of the individuals in the study, 35% were exposed to noise levels of at least 60 decibels at time of joining, and 72% of them remained at their same address throughout the whole study period.
Dr Sørensen concluded, “… 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.”