Air pollution doesn't just affect your physical health — it could mess with your brain chemistry, too. Recent research from the University of Utah found that exposure to pollutants like nitrogen dioxide may have a hand in heightened suicide risk for middle-aged men in Salt Lake County, Utah, a phenomenon that's also been observed in Korea and Vancouver. The new research was inspired partly by Perry Renshaw, who thinks Utah's rampant rates of depression, suicide, and antidepressant use have something to do with it's high altitude.
For the study, psychiatry professor Amanda Bakian and her colleagues compared Salt Lake County's suicide data with daily air pollution levels from the Environmental Protection Agency. They found that men aged 36 to 64 seemed particularly vulnerable to committing suicide following periods when concentrations of nitrogen dioxide in the county were higher. Records of about 1,500 people who committed suicide in Salt Lake County showed that the chances of committing suicide were 20 percent higher for people exposed to nitrogen dioxide just two or three days before their death. Men in particular were also 25 percent more likely to commit suicide after being exposed.
This isn't the only study of its kind. Evidence is stacking up for the psychological impact of bad air including studies where Korean researchers found an increased risk of suicide following exposure to fine particulate matter (a type of air pollutant) and when Vancouver scientists linked emergency room visits for suicide with exposure to high levels of ambient carbon dioxide and other air pollutants. In 2012, the American Psychological Association reported children exposed to small particles of chemicals in the air were more likely to have symptoms of anxiety or depression.
According to Bakian, the explanation may be a lack of oxygen, also known as hypoxia, which is the same biological mechanism behind why depression occurs at higher altitudes. "Air pollution exposure leads to oxidative stress which results in a hypoxic state that alters brain chemistry and neurological function," says Bakian.
But it's key to remember that we don't know if air quality alone increases suicide risk, or if it interacts with other factors, says Bakian. And some people will be more sensitive to the impact of air quality than others, because the pollutants exacerbate their current health conditions. "Some people with pre-existing physical health conditions such as asthma or cardiovascular disease may be especially susceptible to air pushing exposure and may more readily recognize the negative impacts of poor air quality on their physical and emotional health," says Bakian. And if you know you have a genetic predisposition to depression or suicide, be a little more cautious. As for prevention measures, Bakian suggests people become familiar with the air quality monitoring done locally in their regions through online air quality indexes like AirNow, which categories the days air quality based on daily air quality measures.