Suicide and depression linked to air pollution, new analysis suggests

A man in heavy smog in Pristina, Kosovo. Many cities across Kosovo are experiencing high levels of visible air pollution (Credit: Armend Nimani/AFP)

Exposure to air pollution has been linked to a greater risk of depression and suicide – and cutting global levels to the European Union's legal limit could reduce the risk for millions of people.

Links between pollution and poor physical health are well established, but there has been less certainty over mental health. Now a team led by Isobel Braithwaite, of University College London, has closely scrutinized 25 studies published up to late 2017 to produce a major meta-analysis.

Braithwaite's team found that those who live for at least six months in an area with twice the World Health Organization's recommended limit for fine particulate matter (PM2.5) would have around 10 percent more chance of developing depression.

The current WHO guideline for PM2.5 is 10 micrograms per cubic meter of air, averaged over the year – London's average is around 13, Delhi's is 133. London's mayor Sadiq Khan has committed to adopting the WHO guidelines, but the UK government has yet to do so.

London's average for fine particulate matter is above the WHO guideline (Credit: AP Photo/Matt Dunham)

Suicide and causation

The research, published in the journal Environmental Health Perspectives, also found an association between suicide rates and exposure to a larger form of particulate pollution, PM10: each additional exposure of 10 micrograms per cubic meter over a three-day period was linked to a two percent increase in suicide risk.

Braithwaite acknowledges that the analysis explores correlation rather than causation, with many other possible factors at play in the poor mental health of city dwellers, including increased noise and reduced exposure to green spaces. However, she insists the findings add weight to calls to cut pollution.

Campaigners wear masks during an anti-pollution protest outside the city hall in Bucharest, Romania (Credit: AP Photo/Vadim Ghirda)

"We've shown that air pollution could be causing substantial harm to our mental health, making the case for cleaning up the air we breathe even more urgent," said Braithwaite. "Knowing it not only affects physical health but it could also be affecting our mental health, which is something that does affect large numbers of people, I think adds to the weight of the argument for cleaner air and policies that achieve it."

Braithwaite suggests that adopting the EU's limit worldwide could save tens of millions from depression, which affects around 264 million people, according to the WHO. "You could prevent about 15 percent of depression, assuming there is a causal relationship," she says.