FRIDAY, Jan. 6 (HealthDay News) -- Air pollution may increase the risk of type 2 diabetes and high blood pressure in black American women, a new study suggests.

Previous research has shown that air pollution boosts the chances of acute cardiovascular events such as stroke and heart attack, but it hasn't been known whether it also increases the likelihood of chronic diseases such as diabetes and high blood pressure (hypertension).

In this study, researchers examined the link between these chronic illnesses and exposure to nitrogen oxides and particulate matter, also known as particle pollution. Nitrogen oxides are indicators of traffic-related air pollution.

The study included about 4,000 black women living in Los Angeles who were followed from 1995 to 2005. During that time, 531 new cases of hypertension and 183 new cases of diabetes were diagnosed in the women, said study leader Patricia Coogan, an associate professor of epidemiology at the Boston University School of Public Health and the Slone Epidemiology Center at Boston University, and colleagues.

For each increase of 12 parts per billion (ppb) in exposure to nitrogen oxides, there was a 24 percent rise in the risk of diabetes and an 11 percent rise in the risk of hypertension. Exposure to particle pollution also appeared to increase the risk for having both diseases, but the evidence for this was weaker than for nitrogen oxides.

The study was released online Jan. 4 in advance of publication in an upcoming print issue of the journal Circulation.

Two previous studies suggested that traffic-related air pollution increased the risk of diabetes, but those studies did not include black Americans.

"A link between air pollution and the risks of diabetes and hypertension is of particular importance to African American women, because the incidence of both conditions is almost twice as high in African American women as in white women," Coogan said in a Boston Medical Center news release. She added that black Americans also may tend to live in more highly polluted areas than white Americans.

"In addition, even a modest effect of air pollutants on the risks of hypertension and diabetes will have significant public health impact due to the high incidence of these conditions and the ubiquity of exposure to air pollution," Coogan stated in the news release.

More information

The American Lung Association has more about the health effects of air pollution.