Adults with diabetes at higher risk for cardiovascular problems due air pollution

Researchers from the Harvard School of Public Health and colleagues assessed the effect of high air pollution levels, specifically emissions from coal-burning power plants and diesel vehicles, on Boston-area adults with diabetes.

Their study found that on days when air pollution levels were high, adults with diabetes were at higher risk for cardiovascular problems due to impairments in blood vessel function. These results show a biological mechanism linking particulate pollution and impaired cardiovascular function. The findings appear in the June 7, 2005 issue of Circulation: Journal of the American Heart Association.

The study compared the effect of pollution on 270 greater Boston residents divided into two groups; one positively diagnosed with either type I or type II diabetes and the other comprised of non-diabetic individuals but with a family history of diabetes. To assess blood vessel functioning, an ultrasound device was used to measure how well the participants' arteries were able to expand in response to increased blood flow through the arm.

Impaired blood vessel function is associated with an increased risk for atherosclerosis, heart attacks, stroke, other serious cardiovascular problems and death. On days with either high levels of sulfate particles from power plants or black carbon particles from automobile traffic, the arteries of the diabetics in the study were less able to expand in response to blood flow.

Specifically, on days when sulfate pollution was elevated the researchers found an 11 percent decrease in vascular reactivity among diabetic participants. On days when black carbon concentrations were elevated, diabetic study participants had a 13 percent decrease in vascular reactivity. In comparison, non-diabetics were not affected.

Beginning in the early 1990s researchers at the Harvard School of Public Health showed that particles in the air, predominantly from coal-burning power plants and traffic emissions, were associated with nearly 100,000 cardiovascular related deaths per year. What wasn't clear at that time was a demonstrated mechanism linking particle pollution to an increased risk for heart attacks or death.

Joel Schwartz, senior author of the study and professor of environmental epidemiology at the Harvard School of Public Health said, "This research highlights an important mechanism by which particles can increase the risk of heart attacks and deaths. If particles can impair the function of our arteries, it is understandable that this could increase the risk of death from heart disease. This puts greater emphasis on controlling air pollution sooner rather than later." Schwartz also noted that subjects without diabetes were not affected. "The number of diabetics in the US population is increasing rapidly, suggesting the impact of air pollution is likely to rise. This study shows that both coal-burning powerplants and diesel engines produce dangerous pollutants and should be controlled," said Schwartz. Because everyone did not respond the same, Schwartz highlighted the need for studies to identify other susceptible populations in addition to diabetics.