MONTREAL — Chronic exposure to automobile traffic noise is associated with an increased risk of suicide, researchers from the Swiss Institute of Public and Tropical Health have found.
Chronic exposure to railway noise also increased the risk of suicide, but to a lesser extent. No association was found with air travel noise exposure.
“We know that noise is a stressor, this is what can explain mental health problems, commented Richard Martin, who is scientific adviser to the Direction of environmental health, work and toxicology of the Institute. National Public Health of Quebec. It’s a load of stress that is continual.
The researchers studied data from some 5.1 million people aged 15 and over who were enrolled in the Swiss National Cohort between 2001 and 2015. They also looked at their subjects’ exposure to noise from traffic, rail transport and air transport.
They found that a 10 dB increase in average car traffic noise at home was associated with a 4% increase in suicide risk. This association persisted even following adjusting for exposure to air pollution; the amount of green space around the house; and several socio-economic factors.
The researchers point out, however, that the risk of suicide was lower in subjects who had access to green spaces in urban areas.
But not everyone has the luxury of being able to go to the cottage on the weekend, recalled Mr. Martin.
“The (Swiss) researchers hold that mental health problems in sectors heavily exposed to noise are an element that should be given more consideration in our public policies, he commented. More needs to be done to reduce exposure to transport noise.”
Suicide risk began to increase as soon as noise exposure reached 50 dB, or even earlier, the researchers wrote, an exposure higher than that deemed safe by the World Health Organization. The observed associations were stronger in women than in men.
Noise might harm mental health by interfering with sleep quality, increasing stress hormone levels, impairing brain function, or making the individual feel out of control on its environment, the Swiss researchers said.
The brain interprets noise as a potential threat, and chronic exposure to noise can lead to constant restlessness and an inability to handle stress, they added.
“We believe that our results should not be interpreted as suggesting that transport noise has a direct influence on suicide or suicidal behavior, but rather that suicide, as a surrogate for underlying mental disorders, is associated with exposure to transport noise”, specify the researchers.
The association between noise and mental health “is not fortuitous”, recalled Richard Martin, and researchers have been looking more closely at it for the past twenty years.
For example, they are trying to determine whether pre-existing mental health problems might increase susceptibility to noise, or whether exposure to noise leads to the development of mental health problems over time.
“We are more on this path now, he said. We observe more (…) mental health problems in the sectors that are most heavily exposed to noise.”
The findings of this study were published by the scientific journal Environmental Health Perspectives.