Sara D. Adar, ScD, MHS, from the University of Michigan, in Ann Arbor, and colleagues examined the association between concentrations of fine particulate matter (PM2.5) and intima-medial thickness (IMT, as measured by ultrasound) of the common carotid artery in 5,362 individuals without pre-existing cardiovascular disease (45 to 84 years old) in six U.S. metropolitan areas.
The researchers found that carotid IMT increased by an average of 14 µm/y. After adjusting for factors such as smoking and age, higher average levels of residential PM2.5 were associated with increased IMT progression, but only among individuals in the same metropolitan area. Within the same metropolitan area, living at a residence with 2.5 µg/m³ higher levels of residential PM2.5 was associated with a 5.0 µm/y increased IMT progression annually compared with living in less polluted regions. Greater reductions in PM2.5 were associated with slower IMT progression.
"In a large prospective cohort study of adults without pre-existing cardiovascular disease, we found evidence that individuals with higher long-term residential concentrations of PM2.5 experience a faster rate of IMT progression as compared to other people within the same metropolitan area," Adar and colleagues conclude.