Experts call for action as study links pollution to suicide and depression
EXPOSURE to high levels of air pollution increases the risk of depression and suicide, according to a new analysis.
University College London researchers reviewed nine studies analysing the link between emissions and mental health.
They found that being exposed to a small pollutant known as PM2.5 was associated with a higher chance of depression.
Exposure to slightly larger pollutant called PM10 was linked to an increased risk of suicide.
Study lead author Dr Isobel Braithwaite, of UCL Psychiatry and UCL Institute of Health Informatics, 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.
“Here, we’re showing that air pollution could be causing substantial harm to our mental health as well, making the case for cleaning up the air we breathe even more urgent.”
World Health Organisation guidelines recommend that PM2.5 should be kept under 10 micrograms per cubic metre.
People living in UK cities are exposed to around 12.8 micrograms per cubic metre of average particulate matter.
The researchers found an increase of 10 micrograms per cubic metre of PM2.5 was associated with an approximately 10% increase in the odds of depression.
They believe that lowering average air pollution levels to the WHO-recommended limit could reduce the risk of depression among those living in the cities by roughly 2.5%.
The findings, published in the Environmental Health Perspectives journal, also show evidence of an association between shortterm changes in PM10 exposure and the number of suicides.
The scientists said the risk of suicide appeared to be “measurably higher” on days when PM10 levels were high over a three-day period, with figures showing a 2% increase in risk for each 10 micrograms per cubic metre rise in the average pollution level.
The researchers conceded that they could not yet confirm whether air pollution directly caused mental health problems.
However, they stressed there were “a number of biologically plausible mechanisms that may underlie such a link”. Dr Braithwaite explained: “These (mechanisms) include the fact that exposure to air pollution increases the levels of inflammation within the brain.
“This has been linked with depression and other mental health problems through impacts on brain development and, potentially, through impacts on stress hormone production.
“We also can’t rule out the possibility that some or all of the relationship is due to factors associated with air pollution levels and depression risk which were not accounted for by the studies, such as noise pollution or access to green space.”