Long-term Air Pollution Exposure and Markers of Cardiometabolic Health in the National Longitudinal Study of Adolescent to Adult Health (Add Health)

Background: Air pollution exposure is associated with cardiovascular morbidity and mortality. Although exposure to air pollution early in life may represent a critical window for development of cardiovascular disease risk factors, few studies have examined associations of long-term air pollution exposure with markers of cardiovascular and metabolic health in young adults.

Objectives: By combining health data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) with air pollution data from the Fused Air Quality Surface using Downscaling (FAQSD) archive, we: (1) calculated multi-year estimates of exposure to ozone (O) and particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM) for Add Health participants; and (2) estimated associations between air pollution exposures and multiple markers of cardiometabolic health.

Methods: Add Health is a nationally representative longitudinal cohort study of over 20,000 adolescents aged 12-19 in the United States (US) in 1994-95 (Wave I). Participants have been followed through adolescence and into adulthood with five in-home interviews. Estimated daily concentrations of O and PM at census tracts were obtained from the FAQSD archive and used to generate tract-level annual averages of O and PM concentrations. We estimated associations between average O and PM exposures from 2002 to 2007 and markers of cardiometabolic health measured at Wave IV (2008-09), including hypertension, hyperlipidemia, body mass index (BMI), diabetes, C-reactive protein, and metabolic syndrome.

Results: The final sample size was 11,259 individual participants. The average age of participants at Wave IV was 28.4 years (range: 24-34 years). In models adjusting for age, race/ethnicity, and sex, long-term O exposure (2002-07) was associated with elevated odds of hypertension, with an odds ratio (OR) of 1.015 (95% confidence interval [CI]: 1.011, 1.029); obesity (1.022 [1.004, 1.040]); diabetes (1.032 [1.009,1.054]); and metabolic syndrome (1.028 [1.014, 1.041]); PM exposure (2002-07) was associated with elevated odds of hypertension (1.022 [1.001, 1.045]).

Conclusion: Findings suggest that long-term ambient air pollution exposure, particularly O exposure, is associated with cardiometabolic health in early adulthood.