London: People exposed to high levels of air pollution are more likely to experience depression or commit suicide, according to a study that reviewed data from 16 countries. Published in the journal Environmental Health Perspectives, this is the first systematic review of evidence connecting air pollution and a range of mental health problems.
Researchers from the University College London (UCL) in the UK found that, if the relationship with depression reported in some of these studies is causal, then reducing global average exposure to fine particulate matter (PM2.5) from 44 microgrammes per cubic metre (µg/m3) to 25 µg/m3 could result in a 15 per cent reduction in depression risk worldwide.
The World Health Organization (WHO) guidelines recommend that fine particulate matter pollution -- small airborne particles that can include dust and soot -- should be kept under 10 µg/m3, the researchers said.
"We already know that air pollution is bad for people's health, with numerous physical health risks ranging from heart and lung disease to stroke and a higher risk of dementia," said the study's lead author, Isobel Braithwaite from UCL.
The researchers analysed studies that had investigated the association between particulate matter pollution and five different adverse mental health outcomes in adults. They identified 25 studies that fitted their criteria, nine of which were included in the primary analyses.
The team found that a 10 µg/m3 increase in the average level of PM2.5 people were exposed to over long periods was associated with an approximately 10 per cent increase in their odds of depression.
"We found quite consistent results across the studies we reviewed that analysed the relationship between long-term air pollution exposure and depression, even after adjustment for many other factors which could explain the association," Braithwaite said.
The risk of suicide appears to be measurably higher on days when PM10 levels have been high over a three-day period than after less polluted periods, the researchers said. The studies into short-term changes in suicide risk accounted for confounding factors such as weather changes, and day of the week.
--PTI
