Ambient particulate matter exposure and children's blood pressure in rural California, 2019-2022

Elevated blood pressure (BP) in children is a risk factor for adult hypertension and is increasing globally. Ambient particulate matter (PM) is associated with increased BP in children in urban areas, but data from rural regions are sparse. The Children's AIRE study enrolled children 6-8 years in 2017-2019 and collected data bi-annually through Spring 2022. Residential addresses were spatially linked to regulatory air pollution monitors to determine long-term (12-month) and short-term (7-day) exposure to PM 2.5 and PM 10 . Systolic BP (SBP) and diastolic BP (DBP) were measured up to five times in 592 children, standardized, and categorized as normal or elevated/hypertensive. We used linear mixed models to evaluate associations between PM exposures and 1) continuous BP and 2) risk of elevated/hypertensive SBP. In adjusted models, exposure to an additional 38 days (the interquartile range) in the prior year of daily average PM 10 > 50 μg/m 3 was associated with a 1.1 mmHg (95% CI 0.8, 1.5) increase in DBP and a 0.9 mmHg (95% CI 0.3, 1.5) increase in SBP. Children exposed to the highest quartile of average short-term PM 2.5 and PM 10 levels had a 5.8 percentage point (95% CI 0.4%, 11.2%) and 5.9 percentage point (95% CI 0.2%, 11.6%) increase in risk of elevated/hypertensive SBP, respectively, compared to children in the lowest quartiles of exposure. Long-term exposure to PM may lead to increased BP in rural children, while short-term exposures may raise the risk of elevated or hypertensive levels of SBP. These results suggest that air pollution can impact children's cardiovascular health.