Pediatric emergency visits and short-term changes in [P.M.sub.2.5] concentrations in the U.S. State of Georgia

Background: Associations between pediatric emergency department (ED) visits and ambient concentrations of particulate matter [less than or equal to] 2.5 µm in diameter ([PM.sub.2.5]) have been reported in previous studies, although few were performed in nonmetropolitan areas. OBJECTIVE: We estimated associations between daily [PM.sub.2.5] concentrations, using a two-stage model that included land use parameters and satellite aerosol optical depth measurements at 1-km resolution, and ED visits for six pediatric conditions in the U.S. state of Georgia by urbanicity classification. METHODS: We obtained pediatric ED visits geocoded to residential ZIP codes for visits with nonmissing [PM.sub.2.5] estimates and admission dates during 1 January 2002-30 June 2010 for 2- to 18-year-olds for asthma or wheeze (n = 189,816), and for 0- to 18-year-olds for bronchitis (n = 76,243), chronic sinusitis (n = 15,745), otitis media (n = 237,833), pneumonia (n = 52,946), and upper respiratory infections (n = 414,556). Daily ZIP code-level estimates of 24-hr average [PM.sub.2.5] were calculated by averaging concentrations within ZIP code boundaries. We used time-stratified case-crossover models stratified on ZIP code, year, and month to estimate odds ratios (ORs) between ED visits and same-day and previous-day [PM.sub.2.5] concentrations at the ZIP code level, and we investigated effect modification by county-level urbanicity. RESULTS: A 10-µg/[m.sup.3] increase in same-day [PM.sub.2.5] concentrations was associated with ED visits for asthma or wheeze (OR = 1.013; 95% CI: 1.003, 1.023) and upper respiratory infections (OR = 1.015; 95% CI: 1.008, 1.022); associations with previous-day [PM.sub.2.5] concentrations were lower. Differences in the association estimates across levels of urbanicity were not statistically significant. CONCLUSION: Pediatric ED visits for asthma or wheeze and for upper respiratory infections were associated with [PM.sub.2.5] concentrations in Georgia. http://dx.doi.org/10.1289/ehp.1509856.
Introduction Efforts to model ambient air quality have progressed rapidly in recent years. One area that has been advanced is the estimation of particulate matter ≤ 2.5 µm in diameter [...]