Air pollution, particularly fine particulate matter PM2.5 and PM10 and nitrogen dioxide, may be associated with an increased risk of death by suicide and suicidal thoughts. This was the conclusion of the authors of a systematic review and pooled analysis of previously published studies, with the findings presented in the Journal of Epidemiology & Community Health.
The researchers analyzed studies published in English between January 2010 and April 2024. Of the 287 studies selected for detailed review, 45 met the criteria for analysis: 33 focused on deaths by suicide, seven on suicidal thoughts, and five on suicide attempts.
Most of the studies examined exposure to air pollution — 38 studies in total. Three focused on water pollution, three on noise pollution, and one on light pollution.
For the pooled statistical analysis, the researchers used data from 29 studies. The strongest associations were found between short-term exposure to PM2.5 and PM10, as well as long-term exposure to PM2.5 and nitrogen dioxide (NO2), and the risks of suicide, suicide attempts, and suicidal thoughts.
A review of the remaining studies also suggested possible associations between suicidal behavior and exposure to other air pollutants, including sulfur dioxide and ozone, as well as noise pollution. However, the researchers were unable to pool the findings on water and light pollution because of the small number of available studies and substantial differences in assessment methods.
The scientists propose several possible mechanisms that could explain these associations. Some air pollutants, as well as arsenic, lead, lithium, and nitrates found in contaminated water, have been linked to inflammatory processes and nervous system damage that may affect brain function, mood, and resilience to stress. Noise and light pollution, in turn, may increase stress levels and disrupt natural biological rhythms.
At the same time, the authors emphasize the limitations of their work. There were relatively few studies for each of the outcomes examined, and their methods and study designs varied considerably. Therefore, the findings indicate a statistical association between environmental pollution and suicidal behavior but do not establish a cause-and-effect relationship.
The researchers believe that environmental factors should be taken into account when developing suicide prevention strategies. In their view, measures to reduce air pollution and other environmental protection initiatives could potentially become part of comprehensive public and mental health policies.
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