Exposure to air pollutants from traffic fossil fuels may heighten the risk of death by suicide, new UK research shows.
Combined data from 29 studies showed that small airborn particulate pollution and nitrogen dioxide were statistically significantly associated with risk of death by suicide.
The researchers point out these pollutants have been linked to effects on the brain – but also that traffic more generally can increase stress levels by disrupting the body clock.
***This expert reaction contains information some readers may find distressing as it refers to data about mental health, suicide and self-harm. If you or anyone you know needs help, support is available now. Call Lifeline on 0800 543 354. ***
The SMC asked NZ experts to comment.
Dr Julie Trafford, Associate Professor for Planetary Health, AUT University, comments:
“This systematic review considers growing international evidence that air pollution may affect not only physical health, but also mental health and wellbeing. The reviewers concluded that exposure to fine particulate matter (PM2.5 and PM10) and nitrogen dioxide (NO₂), particularly longer term, was associated with increased risk of suicide, suicide attempts, and suicidal thoughts.
“This review does not show that air pollution alone causes suicide. Suicide is a complex issue influenced by social, economic, cultural, psychological, biological, and environmental factors. The findings highlight air pollution as one potentially modifiable risk factor that may interact with other determinants.
“This association could be relevant to New Zealand, where suicide remains a major public health concern. We experience high suicide rates compared with many OECD countries, especially among Māori people and youth. Understanding the broad range of factors that may contribute to suicide risk should be a national priority.
“To my knowledge, New Zealand does not yet have local evidence directly linking air pollution to suicide deaths. However, New Zealand studies have demonstrated associations between air pollution and a range of adverse health outcomes, including mental health. Given New Zealand’s suicide burden, this highlights a key need for further research in Aotearoa.
“Health impacts of air pollution raise important questions about environmental equity and justice: Those generating the pollution are often not those who experience the harm. Exposure often falls disproportionately on communities living near major transport corridors, industrial areas, or other pollution sources.
“The good news for us is that New Zealand generally enjoys better air quality than many countries represented in this review. However, traffic emissions, winter home heating, industrial activities, and wildfire smoke remain as challenges. Cleaner air certainly delivers benefits that extend beyond respiratory and cardiovascular health, including supporting mental wellbeing and more resilient communities.
“Conflict of interest statement: “I declare that I have no actual, potential, or perceived conflicts of interest in relation to this comment, and that my views are provided independently and in the interests of evidence-informed public discussion.”
Dr Joel Rindelaub, aerosol chemist, University of Auckland, comments:
“We know that exposure to air pollution can affect the brain. When we breathe in oxygen, it goes from our lungs to the heart and then pumped straight to the brain. As it turns out, some air pollutants may be able to take the exact same journey.
“There is evidence to suggest that exposure to PM2.5 is linked to mental disorders, such as dementia, reduced intelligence levels, impaired brain development in children, schizophrenia, bipolar and personality disorders, depression, and possibly autism.
“With possible links to mood and behaviour, the recent study by Jones and coworkers used a meta analysis to show that both short term and long term exposure to air pollutants were correlated with death by suicide, attempted suicide, and suicide ideation.
“While more research is needed, these results add to the body of evidence that air pollution has a much larger impact than just to the lungs.”
Conflict of interest statement: “No conflicts of interest to declare.”