Diabetics Have Higher Risk of Adverse Cardiovascular Effects from Particulate Air Pollution

Marie S. O’Neill, Ph.D., Diane E. Gold, MD, Antonella Zanobetti, Ph.D., and Joel Schwartz, Ph.D.
Harvard School of Public Health
T32ES07069, P01ES09825, and P30ES000002

Background: Evidence has been mounting over the past decade that particulate air pollution exposure is an important health risk for those with cardiovascular disease and other chronic conditions, including diabetes. The endothelium, the smooth layer of cells that line blood vessels and the heart, may be one target of particulate matter. The smallest particles have been shown to move from the lungs into the circulation where they may have their effects. These effects include the generation of reactive oxygen species, such as free radicals and peroxides, and the resulting oxidative damage to tissues.

Advance: In a study funded in part by NIEHS, investigators at the Harvard School of Public Health determined that diabetics had impaired blood vessel reactivity on days when sulfate and black carbon particles were highest. In general sulfate particles are generated by coal burning power plants; black carbon is the result of automobile traffic. To test vascular reactivity, the researchers employed a standard technique called brachial artery ultrasound in which blood flow to the arm was blocked with a blood pressure cuff. When the cuff was removed and blood flow restored, the ultrasound technique determined the diameter of the blood vessel. On days with the highest sulfate particle pollution, the diabetic subjects showed an 11% decrease in vascular reactivity and a 13% decrease on days with high black carbon pollution.

Implications: These findings indicate that diabetics may be at higher risk for adverse cardiovascular events during periods of high particulate matter air pollution. In an accompanying editorial, Rajagopalan and colleagues suggest that particulates may have adverse effects by causing abnormalities in the generation of nitric oxide, a gas which relaxes smooth muscle cells found in the heart and arteries, enabling easier blood flow. Further research is necessary to confirm these results and to determine why diabetics are particularly sensitive. In addition to following their health care provider's recommendations on diet, exercise, and medications, diabetics should minimize outdoor physical activity on days with high particulate matter pollution.

Citation: O'Neill MS, Veves A, Zanobetti A, Sarnat JA, Gold DR, Economides PA, Horton ES, Schwartz J. Diabetes enhances vulnerability to particulate air pollution-associated impairment in vascular reactivity and endothelial function. Circulation. 2005 Jun 7;111(22):2913-20.

Rajagopalan S, Sun Q, Chen LC. Particulate pollution and endothelial function: deja vu all over again in the air. Circulation. 2005 Jun 7;111(22):2869-71.