Wake Forest Baptist Medical Center lead researcher Dr John Spangler, a professor of family medicine, said he examined the relationship between air pollution and coal-fired power plant emissions.

“This study raises interesting questions about suicide rates in counties where coal-fired electrical plants operate and suggests that the quality of air can affect people suffering from different mood disorders," Spangler said.

In his research, which was recently published in the Journal of Mood Disorders, Spangler said he looked at the air level contaminates of 20 North Carolina counties where coal-fired electricity plants existed.

He used 2000 US Census data for the compilation as well as mortality rates from 2001 through 2005 from the state’s Center for Health Statistics and US Environmental Protection Agency.

His findings included a higher overall county-level suicide rate in North Carolina, some 12.4 per 100,000 of population, versus that of the national population’s 10.8 per 100,000.

His study also concluded that for each additional coal-fired plant per county there were two additional suicides per population of 100,000 annually.

Because there were 20 coal-fired facilities in the state at the time of the study, it equated to about 40 suicides per 100,000 people per year that stemmed from those plants.

When he applied the state's year 2000 population of 8,049,313, he found approximately 3220 suicides annually tied to coal-fired generation.

“The presence of a coal-fired electricity plant correlated with airborne levels of nickel, mercury, lead, chromium, cadmium, beryllium and arsenic," Spangler said.

He said his study was the first to show a tie between the existence of coal-fired electricity plants and population-level suicide rates.

“Because suicide might be associated with environmental pollution, this study may help inform regulations not only of air pollutants but also of coal-fired electrical power plant emissions,” Spangler said.

The researcher and physician said his work was subject to various limitations because it examined only county-level characteristics and there was no control for factors in individual residents.

“Still, it raises the interesting question of whether suicide in a given population is related to the presence or absence of coal-fired electricity plants and the air quality," Spangler said.

"Further research is needed to understand what factors related to coal burning actually are at play and suggest that tighter regulation of coal-fired power plant emissions might cut down on county suicide rates in North Carolina."