Air Quality and Asthma Hospitalization: Evidence of PM2.5 Concentrations in Pennsylvania Counties

According to the World Health Organization, 235 million people around the world currently suffer from asthma, which includes approximately 25 million in the United States. There is substantial epidemiological evidence indicating linkages between outdoor air pollution and asthma symptoms, more specifically between concentrations of particulate matter and asthma. Using county level data for 2001-2014, a spatial panel framework is imposed based upon prevailing wind patterns to investigate the direct and indirect impacts of PM2.5 concentration levels on asthma hospitalization in Pennsylvania. This model controls for population density, precipitation, smoking rate, and population demographic variables. Results show that PM2.5 concentrations as measured at the county level have positive direct and indirect effects on asthma hospitalization. A one-unit increase in PM2.5 in one Pennsylvania county will add, on average $1.29M ($754,656 direct and $539,040 indirect) to total annual asthma hospitalization costs with the state of Pennsylvania. This study highlights the need for realistic and accurate impact analyses of ambient air pollution on asthma that reflects the impacts on neighboring regions as well. In order to capture the spillover effects of health-related impacts from PM2.5 pollution, a wind direction algorithm to identify appropriate neighbors is important.