Associations of PM2.5 Source Concentrations with Childhood Asthma Emergency Department Visits in the U.S. State of Georgia: A Case-Crossover Study

摘要

Background A novel hybrid air quality model that provides complete spatial coverage of PM2.5 source concentrations throughout the U.S. State of Georgia was used to investigate associations of air pollution sources with childhood asthma exacerbations. Objectives Estimate and compare associations of 12 PM2.5 source concentrations (i.e., contributions of emissions from motor vehicles, power plants, etc. on PM2.5 concentrations) with childhood asthma Emergency Department (ED) visits. Methods ED visits for asthma or wheezing (N=122,414) among children and adolescents (age <18 years) were obtained from patient claims records (in 2005 and 2007). Daily average PM2.5 concentrations from 12 sources were estimated using a hybrid chemical transport (CTM)-receptor model fused with observations from stationary monitors. In the case-crossover study, odds ratios for 3-day moving average PM2.5 concentrations were estimated using conditional logistic regression, matching on day-of-week and month, and adjusting for average temperature (3-day moving average), water vapor mixing ratio (3-day moving average), and Federal holidays. Results We observed positive associations between several PM2.5 sources and asthma ED visits. For example, per interquartile range increase in the source contribution, odds ratio estimates were 1.014 (95% CI: 1.008, 1.020) for dust; 1.029 (95% CI: 1.020, 1.039) for metals, and 1.044 (95% CI: 1.027, 1.063) for natural gas. These sources comprise 5.2%, 2.2%, and 6.5% of total PM2.5 mass, respectively. Heterogeneity in odds ratios across sources could reflect differences in the importance of sources in triggering asthma exacerbations. Because the CTM has uncertainties in the emissions and meteorology inputs and in the modeling of atmospheric processes, such conclusions are tentative. Conclusions Short-term increases in the concentrations of PM2.5 from several sources were associated with increases in childhood asthma ED visits.