It is known that fine particle air pollution is associated with an increased risk of cardiovascular disease; a study by Sara Adar, and colleagues (University of Washington/University of Michigan), published in this week's PLoS Medicine, takes this association further by showing that older people living in areas with long-term air pollution, or even exposed to short term pollution, are more likely to have narrowing of their retinal arterioles — microvascular changes associated with an increased risk of cardiovascular disease.
The authors took digital retinal photographs of participants in the Multi-Ethnic Study of Atherosclerosis—which includes people aged 45 years of various ethnic backgrounds who had no cardiovascular disease symptoms when they enrolled in the study—to measure the diameter of retinal blood vessels. The authors modeled the long-term outdoor concentration of fine particle pollution at each participant's house for the 2-year period preceding the retinal examination; outdoor measurements taken the day before the examination provided data on short-term fine particle pollution levels. Of the 4,607 participants for whom complete data was available, retinal arteriolar diameters were narrowed among those who lived in regions with increased levels of long- and short-term fine particle pollution. In addition, increased retinal venular diameters were weakly associated with long-term (but not short-term) high concentrations of fine particle pollution.
The authors conclude: ''Residing in regions with higher air pollution concentrations and experiencing daily increases in air pollution were each associated with narrower retinal arteriolar diameters in older individuals.'' They continue: "These findings support the hypothesis that important vascular phenomena are associated with small increases in short-term or long-term air pollution exposures, even at current exposure levels, and further corroborate reported associations between air pollution and the development and exacerbation of clinical cardiovascular disease."