Lowering short-term PM2.5 exposure reduces respiratory healthcare utilization among children in Washington State

Background: Fine particulate matter (PM2.5) exposure, even at low levels, increases the risk of many adverse health outcomes. Few studies have evaluated how lowering children’s short-term PM2.5 exposure impacts their healthcare utilization. Methods: We used daily all-cause respiratory and asthma-related emergency department (ED) visit data from Washington’s syndromic surveillance system for 2020-2023. We conducted a quasi-Poisson time series analysis and applied parametric g-computation to estimate the change in respiratory and asthma-related visits among children under different hypothetical interventions on the day-prior PM2.5 concentrations. Interventions corresponded to 2025 U.S. EPA Air Quality Index (AQI) breakpoints for PM2.5 and an additional low exposure scenario (24-hour average, hourly maximum over the day, and previous 12-hour average concentrations of 5, 9, 35.5, and 55.5 µg/m3). Results: There were 426,415 and 60,932 all-cause respiratory and asthma-related ED visits, respectively, among children from 2020 to 2023. All hypothetical interventions on the previous 24-hour average PM2.5 concentration resulted in fewer all-cause respiratory and asthma-related ED visits among children. The largest reduction in visits was seen among children aged 0-4 and 5-11. If the previous day’s 24-hour average PM2.5 concentration was ≤ 5 µg/m3, we estimated 2.2 (95% CI: 0.2, 4.2) fewer all-cause respiratory visits for ages 5-11 and 4.5 (95% CI: 0.2, 8.9) fewer asthma-related visits for ages 0-4 per 1,000 visits. If the previous day’s maximum PM2.5 concentration was ≤ 5 µg/m3, we estimated 10.0 (95% CI: 3.1, 16.8) fewer asthma-related visits for ages 0-4 and 7.6 (95% CI: 1.4, 13.8) fewer for ages 5-11 per 1,000 visits. Results for different PM2.5 thresholds, time averages, and regions were consistent with the main findings. Conclusion: Any reduction in short-term PM2.5 would result in respiratory emergency department visits prevented in children, with the greatest benefit seen for the largest PM2.5 reductions.