Traffic noise 'could shorten life'
Traffic noise is more than a sleep-disturbing nuisance - it can shorten your life, new research suggests.
Researchers found an association between long-term exposure to the roar of road traffic and death rate, as well as the risk of stroke.
People exposed to daytime traffic noise louder than 60 decibels (dB) were 4% more likely to die than those living in areas where noise levels were less than 55 dB.
The extra deaths mostly involved heart or artery disease - which could in turn be linked to raised blood pressure, sleep problems and stress brought on by noise, the scientists claim.
A total of 8.6 million people living in London between 2003 and 2010 provided data for the study, reported in the European Heart Journal.
Lead scientist Dr Jaana Halonen, from the London School of Hygiene & Tropical Medicine, said: "Road traffic noise has previously been associated with sleep problems and increased blood pressure, but our study is the first in the UK to show a link with deaths and strokes.
"This is the largest study of its kind to date, looking at everyone living inside the M25 over a seven-year period. Our findings contribute to the body of evidence suggesting reductions in traffic noise could be beneficial to our health."
The World Health Organisation defines 55dB as a noise level that can cause health problems in a community. In London, more than 1.6 million people are exposed to daytime road traffic noise louder than this threshold.
Although 55dB is roughly equivalent to listening to a loud conversation, research suggests that continuous noise at this level may be harmful.
The study also found that adults living in areas with the noisiest daytime traffic were 5% more likely to be admitted to hospital for stroke than those from quieter neighbourhoods.
For the elderly, this increase in risk rose to 9%.
Between 2003 and 2010, a total of 442,560 adults from the study population died from all causes, of whom 291,139 were elderly.
The scientists looked levels of road traffic noise between 7am and 11pm, and at night between 11pm and 7am, across a range of different postcodes and correlated their findings with death and hospital admission rates.
A number of factors - including individuals' age and sex as well as ethnicity, smoking levels, air pollution and socio-economic deprivation - were taken into account.
Commenting on the findings, Professor Francesco Cappuccio, chair of Cardiovascular Medicine and Epidemiology at the University of Warwick, said: "The results do not imply a direct cause-effect relationship. However, they are consistent with other evidence to suggest a possible causal link.
"For instance, it has been well established that nocturnal traffic noise disrupts sleep quantity and quality. If sustained over time, these disturbances, like sleep deprivation, have been associated with a 12% increased risk of all-cause mortality, mainly due to a 15% increase in stroke events and high blood pressure.
"Public health policies must pay more attention to this emerging evidence."
Dr Tim Chico, consultant cardiologist at the University of Sheffield, said: " This study cannot and does not prove that noise causes cardiovascular disease, although its findings are consistent with other studies showing that noise increases blood pressure, and this could contribute to developing cardiovascular disease.
"There may be other factors that link high noise areas with cardiovascular disease, and it is difficult to take all of these into account. Nevertheless, given what we know about traffic emissions increasing heart disease, we should remember that travelling by foot or bike is definitely healthier - both for you and for the people around you."
Professor Jeremy Pearson, associate medical director at the British Heart Foundation, said: "This carefully conducted study shows that there is a detectable, but very small, excess risk of cardiovascular death amongst people chronically exposed to greater levels of traffic noise.
"The investigators tried to take account of other related factors, in particular traffic-generated air pollution - which is already known to significantly increase risk.
"Their results suggest that reducing air pollution from traffic is more important for heart health than reducing noise."