Study to Determine if Air Pollution Accelerates Development of Cardiovascular Disease

July 6, 2005

WINSTON-SALEM, N.C. – Piggybacking on a major national study, scientists at Wake Forest University School of Medicine and several other centers will try to determine the degree to which air pollution accelerates development of cardiovascular diseases.

“The results of this new study, called MESA Air, can be used in future efforts to better define air pollution standards on both an individual and community basis,” said Gregory L. Burke, M.D., M.S., professor and chairman of the Department of Public Health Sciences at Wake Forest.

With $30 million in funding from the U.S. Environmental Protection Agency, the researchers will incorporate air pollution assessments in ongoing efforts that are following 6,814 participants from the six-city Multi-Ethnic Study of Atherosclerosis (MESA), a 10-year study that began in 1999. Participants from the ancillary MESA Family study and three new MESA Air study sites will bring the total number followed to 8,700.

Forsyth County, N.C., is one of six MESA study sites. The others are Los Angeles, New York, Chicago, Baltimore and St. Paul. In Los Angeles, in addition to the existing site, additional participants will be recruited from coastal parts of the city that have less pollution, and from a more central area with more pollution. Additional participants from New York will be recruited from an area with more pollution.

In atherosclerosis, also called hardening of the arteries, deposits of fatty substances, cholesterol, calcium and other substances build up in the inner lining of an artery. The narrower arteries are susceptible to blockages, which are related to heart attacks and most strokes.

The researchers will be measuring the effect of repeated exposure over a 10-year period to six major air pollutants: particulate matter (smoke, soot, airborne dirt and dust), sulfur dioxide, ozone, carbon monoxide, nitrogen dioxide and lead. They will be measuring air pollution levels both outside participants’ homes and at fixed monitoring stations in each community.

“Forsyth County has some of the highest ozone levels in the whole study,” Burke said.

In MESA, researchers are using sophisticated imaging devices to detect atherosclerosis before there are symptoms – which they call sub-clinical atherosclerosis, including CT scanning to find calcification of coronary arteries and ultrasound measurements of the wall thickness of carotid arteries in the neck.

But the researchers also will be monitoring heart attacks and strokes and other cardiovascular “events,” trying to determine whether long-term exposure to air pollution accelerated development of atherosclerosis, progressively increasing the likelihood of heart attack or stroke, or whether relatively recent exposure to air pollution triggered the event.

MESA Air is called a prospective study, because the researchers will make initial measurement of sub-clinical atherosclerosis and chart the progression of atherosclerosis against actual measurements of the air pollution over a 10-year period.

Burke noted the health effects caused by two catastrophic pollution events – in the Meuse Valley in Belgium on Dec. 1-5, 1930, where several thousand people experienced an acute pulmonary attack and 60 people died in two days, and the Dec. 5-9, 1952 London smog, where as many as 12,000 deaths were attributed to pollution. In both cases, sulfur dioxide was a key ingredient.

“This study seeks to better understand the importance of more moderate longer-term elevations of air pollution on cardiovascular diseases,” said Burke, principal investigator for the Forsyth County portion of the study. The national principal investigator for MESA Air is Joel Kaufman from the University of Washington in Seattle.

MESA is multi-ethnic because it includes white, black, Hispanic and Asian participants selected from populations in the six sites.


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