Nate Berg is a freelance reporter and a former staff writer for CityLab. He lives in Los Angeles.
Louder streets have been linked to greater risk of cardiac arrest.
This just in from the Traffic Kills Department: researchers have found that exposure to the sounds of car traffic significantly increases the risk of heart attack.
Looking at people who've suffered heart attacks and the traffic noise levels in their neighborhoods, a team of Danish researchers found that heart attacks were more likely to occur in noisier areas. For every 10 decibels of increase in traffic noise, the risk of heart attacks rises 12 percent. Their results were published recently in the journal PLoS ONE.
Out of a sample group of more than 50,000 people 50 and older living in Denmark, the researchers identified 1,600 first-time heart attacks between 1993 and 2006. Based on these peoples' residential histories, the researchers developed an estimation of their exposure to both residential traffic noise and air pollution. Confirming previous work, the researchers found a strong association between the incidence of cardiac arrest and people living in areas with road traffic noise above the 50-decibel range, which is noticeable but not roaring. This study is the first to show that the risk of heart attack increases as road traffic gets louder.
The authors note that the study adjusted for potential confounding conditions, including age, sex, education, lifestyle, railway and airport noise. The association between road noise and heart attack was still present after these adjustments.
However, it's also notable that a variety of other unhealthy conditions could be identified in the people suffering heart attacks in areas with road noise above 60 decibels, about as loud as a normal conversation. (Traffic in midtown Manhattan is about 75 to 80 decibels [PDF].)
Cases had higher BMI and lower education, smoked more, drank more alcohol, ate less fruit and vegetables, were less physically active, had higher blood pressure and total cholesterol, had higher prevalence of diabetes and were exposed to more traffic noise and air pollution as compared to the whole cohort. Participants living at residences with more than 60 dB from road traffic noise at baseline had higher BMI and lower education, smoked more, ate less fruit and vegetables, were less physically active and had higher prevalence of diabetes compared to participants living with less than 60 dB.
The researchers don't speculate why this correlation exists, but do note that higher noise levels may cause higher stress levels and greater disturbances in sleep patterns. It's also likely that the lifestyles associated with louder (and presumably more active) places play a role in heart health. So while you can't blame your bum ticker completely on your noisy street, you've now got at least one more reason to be mad about traffic.
Photo credit: Reuters