New York, Feb 13 (IANS): Even short-term exposure to air pollutants such as nitrogen dioxide and fine particulate matter may increase the risk for suicide, especially among men between 36 to 64 years of age, says a new study.

Higher levels of pollution might interact with other factors to increase the risk for suicide, the researchers noted.

"We are not exactly sure why risk of suicide was higher in these two groups," said Amanda Bakian, assistant professor of psychiatry at University of Utah.

"We suspect that it might be because these two groups were either exposed to higher levels of air pollution or that other additional factors make these two groups more susceptible to the effects of air pollution," Bakian added.

Bakian examined the records of more than 1,500 people who died by suicide in Salt Lake County between Jan 1, 2000, and Dec 31, 2010.

The odds of completing suicide were 20 percent higher for people exposed to increased levels of nitrogen dioxide in the two to three days before their deaths.

Similarly, individuals exposed to high concentrations of fine particulate matter (PM2.5) in the two to three days before a suicide experienced five percent higher odds of suicide.

Men experienced a 25 percent increase in the odds of suicide following short-term exposure to nitrogen dioxide and a six percent increase in the odds of suicide following short-term exposure to fine particulate matter.

In addition, the odds of suicide in people between the ages of 36 to 64 increased by 20 percent following short-term exposure to nitrogen dioxide and seven percent following short-term exposure to fine particulate matter.

The study appeared in the American Journal of Epidemiology.