Recent findings add to the evidence that noise pollution may degrade health. A team based at the London School of Hygiene & Tropical Medicine, UK, investigated the effects of living in an area with noisy road traffic.
They analyzed figures on 8.6 million people in London between 2003 and 2010, taking into account levels of road traffic noise from 7:00 a.m. to 11:00 p.m., and from 11:00 p.m. to 7:00 a.m. Noise levels were then cross-referenced with deaths and hospital admissions, taking into account other factors such as individuals’ age and sex, as well as neighborhood characteristics like ethnicity, smoking rate, air pollution, and socioeconomic deprivation.
This indicated that adults (aged 25 and over) and the elderly (aged 75 and over) were four percent more likely to die if they lived in areas with daytime road traffic noise of above 60 decibels, compared with below 55 decibels. The deaths tended to be due to cardiovascular disease, perhaps because of stress from the noise, increased blood pressure, or impaired sleep.
In terms of hospital admission for stroke, adults in areas with daytime traffic noise of more than 60 decibels were five percent more likely to be admitted, compared with those in areas that had less than 55 decibels of noise. This rate increased to nine percent among the elderly in noisy areas.
For nighttime noise, adults unaffected by rates of stroke rose by five percent among the elderly in the noisiest areas. Full details are published in the European Heart Journal.
“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,” commented Dr. Jaana Halonen, lead author.
“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.”
Co-author Dr. Anna Hansell of Imperial College London, UK, added, “From this type of study, we can’t tell for certain what the risks of noise are to an individual, but these are likely to be small in comparison with known risk factors for circulatory diseases like diet, smoking, lack of exercise, and medical conditions such as raised blood pressure and diabetes.
“However, our study does raise important questions about the potential health effects of noise in our cities that need further investigation.”
In addition, the team says the findings are consistent with a large number of previous studies linking road traffic noise and high blood pressure, a leading cause of stroke. Noise can also affect the so-called hypothalamus-pituitary-adrenal axis, leading to increased levels of the stress-related hormone cortisol.
In the long term, these reactions may promote low-grade inflammation and cardiovascular disease. Another possible pathway for damage is via sleep disorders, some of which have been linked to an increased death risk.
The World Health Organization defines daytime road traffic noise levels above 55 decibels as a level of community noise that causes health problems. The WHO’s definition of an adverse effect of noise includes “any temporary or long-term lowering of the physical, psychological, or social functioning of humans or human organs.”
In their Guidelines for Community Noise, they state that noise pollution can trigger noise-induced hearing impairment, interfere with communication, disturb rest and sleep, affect mental health and performance, cause annoyance, and interfere with planned activities.
The WHO adds that, to protect populations from the adverse health impacts of noise, they recommend that governments consider the protection of populations from community noise as an integral part of their policy for environmental protection. Governments should also implement action plans for reducing noise levels, for example, by enacting legislation to reduce sound levels and enforcing existing legislation.
They also suggest that, in order to help promote such measures, decision-makers could concentrate on “variables which have monetary consequences,” such as reduced productivity, decreased performance in learning, workplace and school absenteeism, increased drug use, and accidents.
Finally, they say there is a need for continued research to understand community noise and its effects on health. “The main goal for research activities is to improve the scientific basis for policy-making and noise management,” they write. “This will protect and improve the public health with regard to the effects of community noise pollution.”
Halonen, J. I. et al. Road traffic noise is associated with increased cardiovascular morbidity and mortality and all-cause mortality in London. European Heart Journal 24 June 2015 doi: 10.1093/eurheartj/ehv216