Abstract
Little is known about the early-life cardiovascular health impacts of fine particulate air pollution (PM2.5) and oxidant gases. A repeated-measures panel study was used to evaluate associations between outdoor PM2.5 and the combined oxidant capacity of O3 and NO2 (using a redox-weighted average, Ox) and retinal vessel diameter and blood pressure in children living in a region impacted by residential biomass burning. A median of 6 retinal vessel and blood pressure measurements were collected from 64 children (ages 4–12 years), for a total of 344 retinal measurements and 432 blood pressure measurements. Linear mixed-effect models were used to estimate associations between PM2.5 or Ox (same-day, 3-day, 7-day, and 21-day means) and retinal vessel diameter and blood pressure. Interactions between PM2.5 and Ox were also examined. Ox was inversely associated with retinal arteriolar diameter; the strongest association was observed for 7-day mean exposures, where each 10 ppb increase in Ox was associated with a 2.63 μm (95% CI − 4.63, − 0.63) decrease in arteriolar diameter. Moreover, Ox modified associations between PM2.5 and arteriolar diameter, with weak inverse associations observed between PM2.5 and arteriolar diameter only at higher concentrations of Ox. Our results suggest that outdoor air pollution impacts the retinal microvasculature of children and interactions between PM2.5 and Ox may play an important role in determining the magnitude and direction of these associations.
Highlights
Little is known about the early-life cardiovascular health impacts of fine particulate air pollution (PM2.5) and oxidant gases
We explored whether associations between P M2.5 and retinal vessel diameter were modified by concentrations of Ox by running models with an interaction term between PM2.5 and O x, while adjusting for the same set of covariates identified above
We explored whether including a fixed effect for school was necessary to account for potential clustering within schools, but it did not improve model fit based on the minimum Akaike Information Criterion (AIC) so was not included in the final models
Summary
Little is known about the early-life cardiovascular health impacts of fine particulate air pollution (PM2.5) and oxidant gases. A repeated-measures panel study was used to evaluate associations between outdoor PM2.5 and the combined oxidant capacity of O3 and NO2 (using a redox-weighted average, Ox) and retinal vessel diameter and blood pressure in children living in a region impacted by residential biomass burning. Most research on associations between ambient air pollution and cardiovascular outcomes has focused on particulate matter exposure and consistent evidence from epidemiological and animal studies support a causal relationship[1]. Oxidant gases, such as ozone (O3) and nitrogen dioxide (NO2), have been associated with adverse cardiovascular outcomes, results have been less c onsistent[4,5]. Stronger associations between long-term[6] and short-term[7] fine particulate matter air pollution (PM2.5) and mortality were found when the combined oxidant capacity of NO2 and O3 (using a redox-weighted average, O x) was higher, highlighting the importance of considering O x when evaluating P M2.5 health effects
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