Air pollution and hospitalization: an autoregressive distributed lag (ARDL) approach

Air pollution is one of the biggest global environmental problems in urban regions. This study aimed to investigate the validity of the relationship between air pollution and respiratory and cardiovascular hospitalization using time series methods. This time series study was conducted in Isfahan, Iran. We used data of hospitalized cases in three main university hospitals (Alzahra, Noor, Chamran) and air pollution data from 2014 to 2016. We applied the autoregressive distributed lag (ARDL) bounds testing approach of cointegration to examine the relationship between the air pollution and hospitalizations of respiratory and cardiovascular diseases. The results of air quality assessment on the number of respiratory and cardiovascular hospitalization demonstrate that in the case of cardiovascular disease, both in the long run and in the short run, the air quality index has a significant impact on men and women with a bigger impact in the long run compared to the short run. The value of the long-run coefficient indicates the relationship between air pollution index and cardiovascular hospitalization is stronger than respiratory hospitalizations. In the long term, the effect of the air quality index (AQI) on the number of hospitalizations is more than that in the short term. Based on the results, a 10-unit increase in AQI leads to 5.3% increase in the number of respiratory hospitalization. Accordingly, a 10-unit increase in AQI will result in 7.3% increase in the number of cardiovascular hospitalizations.