Air pollution linked to higher suicide risk, international research suggests

Analysis of 29 studies highlights potentially heightened danger from small particulate matter and nitrogen dioxide

Air pollution is associated with an increased risk of suicide and suicidal thoughts, according to research.

Environmental pollution is known to be associated with poorer mental health but its role in suicide risk is less well understood. Scientists at Queen’s University Belfast examined whether air, noise, light, and water pollution could influence the risk of death by suicide and suicidal behaviours.

Their meta analysis of 29 studies found that exposure to airborne small particulate matter and nitrogen dioxide were linked to a heightened risk of death by suicide, suicide attempts and suicidal ideation.

Narrative analysis of a further 16 studies suggested that some other air pollutants such as sulphur dioxide and ozone, as well as noise pollution, were also associated with a higher suicide risk. However, evidence for light and water pollution was inconclusive.

The authors said the findings, published in the Journal of Epidemiology and Community Health, suggested that environmental pollution could be considered in suicide prevention strategies and that suicide prevention should also be viewed as a public health issue.

“These findings bring to attention the critical importance of recognising environmental exposures as modifiable risk factors within suicide prevention efforts,” they said.

“Integrating environmental health into mental health policy, through cross-sectoral collaboration, pollution reduction strategies, and targeted public health interventions, could play a vital role in reducing suicide risk and improving overall population mental wellbeing.”

But other experts expressed caution about the findings. Dr Jess Moody, the senior research and evidence manager at Samaritans, said: “While the reasons for suicide are complex, evidence shows that a variety of factors can impact suicide risk and we must not ignore the environments we live in, particularly inequalities around living conditions. Samaritans welcomes research that helps awareness of how suicide links to wider public health concerns.”

Dr Jon Van Niekerk, the chair of the general adult faculty at the Royal College of Psychiatrists, said the research suggested some forms of air pollution may be associated with a small increase in suicidal behaviour but it did not establish that air pollution itself caused suicidal thoughts or attempts.

He added: “Air pollution is closely associated with other factors which we know can influence mental health, including socioeconomic deprivation, urban living, physical health and housing.

“The study provides further population-level support for reducing harmful air pollution, though the findings should not be seen as supporting individual suicide risk prediction or suggesting that pollution reduction alone could be a suicide prevention measure.”

Dr Rosie Cornish, a senior research fellow in epidemiology and health data science at the University of Bristol, said there were many factors associated with higher levels of air pollution as well as increased risk of suicide.

“If air pollution is not actually a cause of increased risk of suicide then reducing pollution will not help to prevent suicide. The authors do not acknowledge this when drawing their conclusions.”

Dr Stephen Burgess, a professor of biostatistics at the University of Cambridge, said: “This study confuses two fundamentally different concepts: causation and association.

“There are many other factors that could potentially explain the associations observed. For example, areas with higher levels of pollution may differ in other ways that affect suicide risk.

“This research finds factors that are associated with increased suicide risk, but further research is needed to claim that the factors identified are causes of increased risk.”

More than 720,000 people globally die by suicide each year. It is the third leading cause of death among 15– to 29-year-olds, according to the World Health Organization.