"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.