Mental disorders affect almost a billion people around the world and are one of the main causes of suicide, behind it there may also be noise.
In Switzerland, it is estimated that around 1.4 million people suffer from mental health problems and that around 1,000 take their own lives every year. Environmental factors such as air or noise pollution have been linked to adverse health effects such as cardiovascular disease and general well-being. However, solid evidence on the effects of transport noise on mental disorders remains scarce.
For the first time, researchers from the Swiss TPH have assessed the link between transport noise and suicide in Switzerland. The study, published today in the journal Environmental Health Perspectivesanalyzed data from 5.1 million adults from the Swiss national cohort between 2001 and 2015.
The study found that exposure to transport noise at home was linked to an increased risk of death by suicide. For every 10 dB increase in average traffic noise in the home, the risk of suicide increases by 4%. An association with railway noise was also observed, although less pronounced. The observed results were robust even after adjusting for exposure to air pollution, the amount of green space around the home, and various socioeconomic indicators.
Noise as a constant stressor
“We used suicides as an indicator of mental disorders, as we don’t have reliable Swiss data on mental health diagnoses such as depression or anxiety,” explains Benedikt Wicki, a PhD student at the Swiss TPH and first author of the study. “Noise increases mental load, contributing to the development of mental disorders or the aggravation of pre-existing conditions.”
Biological mechanisms by which noise affects mental health include sleep disturbances, increased levels of stress hormones, changes in brain function, or feelings of loss of control. “Our brain registers the noise as a signal of a potential threat and activates the ‘fight or flight’ response. The constant noise of transport at home can agitate us and make us unable to cope with stress,” says Danielle Vienneau, a Swiss researcher at TPH and lead author of the study.
Data from 15 years of studies
The study used data from 5.1 million people older than 15 years from the Swiss National Cohort from 2001 to 2015. The researchers compared these data with exposure to noise from transport sources such as traffic, railroads and the airplanes. Noise exposure data were available for all households in 2001 and 2011, and study participants were assigned based on their place of residence.
Noise reduction measures pay off
The study highlights the importance of addressing the effects of transport noise, air pollution and ecology on health in urban planning and public health policy.
“Our study adds to the growing body of evidence that chronic exposure to transport noise affects our physical and mental well-being,” says Martin Röösli, Head of the Health and Environmental Exposure Unit at Swiss TPH. “Our study shows that noise reduction measures such as speed limits, lighter vehicles and quieter pavements and tires pay off.”
REFERENCE
Suicide and transport noise: a prospective cohort study from Switzerland
