A systematic review and meta-analysis published in the Journal of Epidemiology and Community Health has examined environmental exposure to air pollutants and risk of suicide. The study, by Sophie Marie Jones and colleagues, was published at 23:30 UK time on Tuesday 15 September.
Dr Jon Van Niekerk, Chair of the Royal College of Psychiatrists' General Adult Faculty, said the review adds to evidence suggesting exposure to some forms of air pollution may be associated with a small increase in suicidal behaviour at population level. He said most of the underlying evidence is observational, so the study cannot establish that air pollution itself causes suicidal thoughts or attempts.
Dr Van Niekerk added that air pollution is closely associated with other factors that can influence mental health, including socioeconomic deprivation, urban living, physical health and housing. He said the research should be interpreted with caution because of considerable variation between studies in how pollution exposure and suicidal behaviour were measured.
Dr Stephen Burgess, Professor of Biostatistics at the University of Cambridge, said the study confuses causation and association. He said areas with higher levels of pollution may differ in other ways that affect suicide risk, such as their socioeconomic or urban environment, and that a causal conclusion is only reasonable when there is a like-with-like comparison.
Dr Rosie Cornish, Senior Research Fellow in Epidemiology and Health Data Science at the University of Bristol, said many factors associated with higher air pollution and increased suicide risk could potentially explain the observed associations, including socio-economic deprivation, availability of green space, housing quality and lifestyle factors linked to urban versus rural living.
Dr Van Niekerk said 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.