The effect of air quality on infant morbidity: Evidence from temperature inversions

This paper contributes to the literature on the valuation of environmental effects by considering the impact that short term exposure to high concentration levels of total suspended particulates (TSP) can have on infant morbidity. Utilizing the existence of temperature inversions that are formed randomly by county throughout the Rocky Mountain Region and that vary widely based on weather patterns, this study is able to take advantage of what amounts to extreme shocks to air quality at the county level in order to observe changes in monthly infant inpatient hospitalization throughout every county in both Utah and Colorado over a ten year period. Specifically, for this project, two models using a panel of monthly hospital discharge and temperature inversion data at the county level from January 2004 - April 2014 are employed. The initial model uses county and state-by-year fixed effects to show that increases in PM 2.5 concentrations statistically significantly increase average monthly infant inpatient care with respect to respiratory infection and asthma. The second model corrects for any potential endogeneity in the temperature inversion variable (related to economic and social conditions in the area) through the use of each county’s monthly minimum height of the planetary boundary layer (PBL) as an instrumental variable. Planetary boundary layer data captures the height of each temperature inversion, is strongly correlated with total suspended particulate (TSP) levels, is unrelated to local economic or social conditions, and is available for each county and year as is used in the initial model. As with the initial model, results demonstrating that increases in PM 2.5 concentrations statistically significantly increase average monthly inpatient care with respect to respiratory infection and asthma are expected. 

Keywords: Air Pollution, Health Effects, Instrumental Variables