Study Finds Link Between Pollution and Suicide

Smoke is released into the sky at a refinery in Wilmington, California Bret Hartman/REUTERS

Scientists at the University of Utah have found a link between short-term exposure to pollution and suicide - particularly for middle-aged men.

Examining the deaths of more than 1,500 men and women in Salt Lake City, Utah between 2000 and 2010, the findings draw an association between suicide and exposure to elements that exist in polluted air - nitrogen dioxide and fine particulate matter, small particles that can range from dust to combustible sources that float invisibly in the air.

The study, published yesterday in The American Journal of Epidemiology, was conducted by Amanda Bakian, an assistant professor of psychiatry at the university, and colleagues in the health sector.

Researchers found that there was a 20% increase in the odds of suicide in people who had short-term exposure to nitrogen dioxide in the two or three days prior to their deaths. A 5% increase in the odds was found in those who had exposure to high concentrations of fine particulate matter within that same time frame.

However, research shows that men were 25% more likely to commit suicide after being exposed to nitrogen dioxide and 6% more likely to do so after having exposure to fine particulate matter, a rate that increased by 20% for middle-aged men following nitrogen dioxide exposure, and 7% after being exposed to fine particulate matter.

"We examined the method of suicide, whether it was violent non-violent, the person's gender, and the season in which they committed suicide," Bakian says, "and there was a strong relationship between air pollutants and odds of suicide in men aged 36 to 64 who committed suicide in the spring time, as well as by individuals who died by violent methods."

The reason is unclear, but Bakian says that there is potential that men in that age group have different exposure levels to air pollutants or have characteristics that are unique to them at that time in their life.

However, Bakian clearly states that research does not prove that pollution causes people to commit suicide. Rather, exposure to higher levels of pollution may increase the odds of suicide through the interaction with a variety of other factors at play.

She emphasises that suicide is complex, and believes that further research needs to be done before a definitive reason for the link can be made. "Clearly not everyone is uniformly susceptible to the effects of air pollution," she says. "The exposure required to affect the odds varies across individuals and in some individuals, even low to moderate levels of exposure can result in poor outcomes."

Bakian says there could be personal characteristics that increase the risk, co-occurring medical issues, lifestyle factors or a combination of different characteristics that are unique to men. Alternatively, Bakian says that men may just get more exposure to pollution than women.

According to Bakian, suicide is the eighth cause of death in Utah and the tenth in the United States.

"It is a preventable outcome," she says. "We hope that finding out more about the correlation may help lead to its prevention, as well as interventions in public health." Funding for the research provided in part by the university's Program for Air Quality, Health and Society programme has been expanded to run state-wide.

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