An increase in noise levels from traffic is an accepted inevitability in our daily, urban lives. However, a 2011 study from Denmark, believes that traffic noise may now raise your risk of having a stroke or heart attack. According to the European Heart Journal, a study of more than 57 000 people over 22 years, found that for every 10 decibel increase in traffic noise, the liklihood of a stroke increases by 14%.
The Reason: Acute exposure to noise is believed to activate the sympathetic and endocrine systems, causing changes in heart rate, blood pressure and the subsequent release of stress hormones. The aim of the European Heart Journal study was to further investigate this association between exposure to acute transport noise and the risk of stroke.
The Methodology: 57 053 random people between the ages of 50 and 64 years old, living in Copenhagen, accepted an invitation for the study. A complete residential history was collected and road traffic noise calculated for the years 1990, 1995, 2000, and 2005 for all residential addresses at which the cohort members lived.
The noise model was estimated on geographical coordinates like the height of the floor of the residence and road lines, with information on yearly average traffic, and road type (motorways, rural highways, and roads wider than 6 m) taken into account.
Out of the study participants, 1 881 (3.7%) were admitted to hospital for stroke over the 22 year span. A 10 decibel higher level of road traffic noise was associated with a 14 times higher risk for stroke after adjustment for various risk factors. There was also a significant link between road traffic noise and strokes among cases who were 64 years and older; with a 27% higher risk per 10 decibel higher exposure to noise. Exposure to railway and airport noise was not associated with a higher risk for stroke mostly due to an inability to form an accurate noise model.
While the study is interesting in terms of the potential effects of noise generated by traffic, it would be more interesting to discover the extent to which stress levels affect people while actually driving in traffic. The way some people clutch their steering wheel with white knuckles and stare wide-eyed through their windscreen, suggests driving in traffic could give some people a stroke at 30 years old, never mind 50!