A new study has found that exposure to pollution leads to an increased severity in mental illness.
The study, the most comprehensive of its kind, sampled 13,000 people in London and concluded that even the smallest increase in exposure to nitrogen dioxide increased the risk of needing community-based treatment by 32%, while shooting up the possibility of being hospitalised to 18%.
Although the study focused on London, the researchers said its findings could likely apply to most cities in developed countries, adding that cutting air pollution could benefit millions of people.
The new study, published in the British Journal of Psychiatry, tracked patients in south London from their first contact with mental health services, using high-resolution estimates of air pollution at their homes.
It used the frequency of admission to hospital or visits to community doctors and nurses as a measure of severity.
The team then derived from its data that a small reduction in one pollutant alone could reduce illness, saving the NHS tens of millions a year. Joanne Newbury of the University of Bristol is part of the research team, and she said:
Air pollution is modifiable, and on a big scale as well, reducing population-level exposure. We know there are interventions that can be used, such as expanding low-emission zones. Mental health interventions at the individual level are actually quite difficult.
No safe level
In recent years, the levels of air pollution in London have been on the decline but experts say there are no safe levels - they need to go down as low as possible.
In a recent report, the World Bank estimated that air pollution costs the global economy $5tn a year.
However, this took into account only the well-known damage caused to the heart and lungs. Newbury said more research needs to be done to establish other costs.
Cost evaluations currently only factor in physical health, but we’re seeing more studies demonstrating links with mental health. We think it can be important to include these, because it could tip the scales and make it clearer that investing in reducing air pollution is cost-effective.