Childhood air pollutant exposure and carotid artery intima-media thickness in young adults

Background-: Exposure to ambient air pollutants increases risk for cardiovascular health outcomes in adults. The contribution of childhood air pollutant exposure to cardiovascular health has not been thoroughly evaluated. Methods and Results-: The Testing Responses on Youth study consists of 861 college students recruited from the University of Southern California in 2007 to 2009. Participants attended 1 study visit during which blood pressure, heart rate, and carotid artery intima-media thickness (CIMT) were assessed. Self-administered questionnaires collected information about health and sociodemographic characteristics, and a 12-hour fasting blood sample was drawn for lipid and biomarker analyses. Residential addresses were geocoded and used to assign cumulative air pollutant exposure estimates based on data derived from the U.S. Environmental Protection Agency's Air Quality System database. The associations between CIMT and air pollutants were assessed using linear regression analysis. Mean CIMT was 603 μm (±54 SD). A 2 standard deviation (SD) increase in childhood (aged 0-5 years) or elementary school (aged 6-12 years) O₃ exposure was associated with a 7.8-μm (95% confidence interval, -0.3-15.9) or 10.1-μm (95% confidence interval, 1.8-18.5) higher CIMT, respectively. Lifetime exposure to O₃ showed similar but nonsignificant associations. No associations were observed for PM_2.5, PM₁₀, or NO₂, although adjustment for these pollutants strengthened the childhood O₃ associations. Conclusions-: Childhood exposure to O₃ may be a novel risk factor for CIMT in a healthy population of college students. Regulation of air pollutants and efforts that focus on limiting childhood exposures continue to be important public health goals.