Air pollution has been blamed in an eighth of all deaths worldwide in 2012, and it just got deadlier: On the heels of studies that have produced similar findings in Canada, South Korea, and Taiwan, spikes in air pollution are being linked to spikes in suicides, reports LiveScience. Researchers at the University of Utah report in the American Journal of Epidemiology that acute air pollution, marked by "short-term exposure to nitrogen dioxide and fine particulate matter," led to a 20% increase in the odds of "completing" suicide in the two to three days following those spikes. Suicide "is a preventable outcome, and air pollution could be a modifiable risk factor," says the study leader. One possible link is physical inflammation, notes LiveScience, which can be caused by air pollution and which is increasingly being identified as a risk factor for suicide.
Picking apart the records of the more than 1,500 people who died by suicide in Salt Lake City between 2000 and 2010, researchers found that two groups in particular—men and people between the ages of 36 and 64—had the highest suicide risk after this short-term exposure to higher air pollution. They caution, however, that it's just one study joining a still small body of research, and that the link is not necessarily causal, with many questions lingering. For instance, the link was strongest in the spring and fall, not winter, leading them to believe that other risk factors are at play. And while they controlled for sunlight exposure, the researchers did not directly control for precipitation, which might play a role in pollution levels. (Scientists have identified a genetic component of suicide risk as well.)