Even at currently acceptable levels, air pollution may lead to blocked arteries and stroke.
Only two and a half years into its planned 10-year duration, the MESA study (Multi-Ethnic Study of Atherosclerosis and Air Pollution) already suggests that fine particulate air pollution causes thickening of the arteries.
Researchers in six U.S. cities collected ultrasound exams from 5,362 adults of various ethnicities. The point of the study was to find out whether the heart risks from dirty air go beyond heart attacks triggered by short-term heavy exposure. Preliminary findings suggest that long-term pollution exposure increases stroke risk.
“[P]articipants living in parts of town with [slightly] higher concentrations of fine-particle air pollution would have a 2% relative increase in risk of stroke compared to persons in a less polluted part of the metropolitan area,” concludes a research team led by Sara D. Adar, of the University of Michigan.
How much air pollution is too much? “Our findings are expected to hold even at lower concentrations as past evidence suggests that there is likely no safe threshold for air pollution,” the authors write.
One bright spot: in areas where air pollution dropped, progression to atherosclerosis slowed.