Street noise is so damaging to our psyche

Nearly one billion people worldwide suffer from mental illness and it is also one of the leading reasons for suicide. In Switzerland, an estimated 1.4 million people suffer from mental health problems and about 1,000 people take their own lives every year.

Environmental factors such as air pollution or noise have already been linked to cardiovascular disease or a general impairment of well-being. Researchers from the Swiss Tropical and Public Health Institute (Swiss TPH) have now examined the link between traffic noise and suicides in Switzerland and published their study in the journal “Environmental Health Perspectives”.

Data from 5.1 million adults between 2001 and 2015 shows that exposure to traffic noise in the place of residence led to a higher risk of suicide. Every 10 decibels (dB) increase in average road traffic noise at home increases the risk of suicide by 4 percent. For example, 10 dB difference is the difference between a normal conversation and a vacuum cleaner at a distance of one meter.

“In summary, it can be said that the risk increases continuously from 50 decibels for all traffic sources”, says Swiss TPH researcher Martin Röösli when asked how much noise pollution becomes dangerous. This 50 dB is a mixing value between day and night noise and corresponds to an average noise of almost 50 dB during the day and 40 dB at night. We are more sensitive to noise at night.

There is no specific threshold at which noise not only has psychological consequences, but even causes an acute risk of suicide, says Röösli. “We see a continuous increase in risk.” This means that individual risk factors are crucial. If someone already has many psychological stressors, the risk of suicide is generally high and can become critical with noise. “If someone has little mental stress, the absolute additional risk of a small increase in risk is very low and the likelihood of it becoming critical is correspondingly small,” says Röösli. Ultimately, the main problem is that traffic noise affects a large number of people and therefore, from a public health point of view, even small additional risks are significant overall.

There was also a connection with railway noise, but less pronounced. The results of the study turned out to be solid, even after taking into account other factors such as air pollution, the degree of greening of the immediate living environment and various socio-economic data.

The psyche is damaged because the noise leads to sleep disturbances, an increased release of stress hormones, changes in brain function or a feeling of loss of control. “Our brain registers sound as a sign of potential threat and activates the fight-or-flight response. Constant traffic noise at home can leave you feeling restless and unable to cope with the stress,” says author Danielle Vienneau.

The study shows that noise reduction measures such as speed limits, lighter vehicles and low-noise road surfaces and tires are worth taking to protect our physical and mental well-being, says Martin Röösli of the Swiss TPH. Urban planning and public health policies must take into account the effects of traffic noise, air pollution and green spaces.