Air pollution

Air pollution doesn't just make it hard to breathe – it may also increase the risk that people will take their own lives.

A new study in seven cities across South Korea has uncovered a clear association between suicide and spikes of particulate pollution. Meanwhile, researchers who in the 1990s linked air pollution to asthma in a large group of Taiwanese children have now found that those with the condition were subsequently more likely to have killed themselves.

Suicide is a big problem for South Korea, where the rate per 100,000 people rose from 14 in 1996 to 23 in 2006 – the largest increase in the developed world.
Soot and suicide

To examine the role of pollution, researchers led by Chang Soo Kim of Yonsei University in Seoul linked records of more than 4000 suicides to measurements of PM10 – airborne particles with a diameter of 10 micrometres or less, which include the soot from vehicle exhausts.

Kim's team found that suicides were more common in the two days following a spike in pollution. They considered PM10 measurements on a scale from the highest and lowest levels recorded, calculating that people were 9 per cent more likely to kill themselves following a spike in pollution rising across the middle 50 per cent of recorded values. For people with cardiovascular disease, which has already been linked with particulate pollution, the increase was almost 19 per cent.

South Korea's cities, like many in Asia, are badly blighted by air pollution, and it is unclear whether the effect would be so dramatic in cities that have tighter pollution controls. "Further investigations of low-level exposure to particular matter are needed," says Kim.