Air pollution linked to suicide risk, major study finds
Short-term exposure to fine particles in the air increases the risk of suicide deaths, suicide attempts and suicidal thoughts, according to a meta-analysis published this week. The research, which reviewed evidence on environmental pollution and mental health, found a statistically significant link between several common air pollutants and suicidal behaviour.
The study was carried out by the Queen's University Belfast Public Health Centre and published in the Journal of Epidemiology & Community Health. Researchers analysed data from studies published between January 2010 and April 2024.
What the evidence shows
The meta-analysis examined 45 studies in total, with 29 subjected to statistical analysis. The strongest associations emerged for:
• Short-term exposure to PM2.5 (particles smaller than 2.5 micrometres) and PM10, linked to increased suicide risk in the six months following exposure
• Long-term exposure to PM2.5 and NO2 (nitrogen dioxide), associated with elevated risk over periods longer than six months
The review also identified connections between suicidal behaviour and other pollutants including sulphur dioxide (SO2), ozone (O3), carbon monoxide (CO) and noise pollution. Limited research meant water and light pollution could not be fully assessed.
The biological explanation
The researchers explain that air pollutants cause chronic inflammation and nerve damage, altering brain function. These changes affect mood regulation and reduce the capacity to cope with stress. Contaminated water containing arsenic, lead, lithium or nitrates can produce similar neurological effects.
Noise pollution — particularly nighttime traffic and railway noise — creates chronic stress and disrupts circadian rhythms, contributing to anxiety and depression.
What this means for Portugal
Portugal recorded a suicide mortality rate of 9.9 deaths per 100,000 inhabitants in 2022, up from 8.9 in 2021. Suicide remains the leading cause of death among children and young adults aged 10 to 29. Rates are highest in the Alentejo and Algarve regions, followed by the Centro region.
Air quality data from 2025 shows the average annual concentration of PM2.5 rose to 7.9 µg/m³ — 1.6 times above the World Health Organization's guideline. In Lisbon, the Avenida da Liberdade recorded 40.3 µg/m³ of NO2. Some 94% of Portugal's traffic monitoring stations exceeded WHO recommendations for NO2.
A separate Portuguese study published in Acta Médica Portuguesa in July 2024 found links between long-term air pollution exposure and mental well-being, depression and anxiety nationally, though it did not focus specifically on suicide.
A call for policy change
The Queen's University authors say environmental factors must be recognised as modifiable risk factors in suicide prevention strategies. They call for integrating environmental health into mental health policy through collaboration between sectors.
"Integrating environmental health into mental health policies could play a vital role in reducing suicide risk and improving general mental well-being," the researchers wrote.
The findings align with a March 2026 report from the European Environment Agency, which found that various forms of pollution contribute to depression, anxiety and schizophrenia.
No specific public policies in Portugal currently integrate air quality reduction into suicide prevention programmes.
