Relationship between the number of hospitalized cardiovascular and respiratory disease and the average concentration of criteria air pollutants (CAP) in Ahvaz

This study aims to investigate the relationship between the number of hospitalized cardiovascular and respiratory patients and the average concentration of criteria air pollutants, including NO₂, SO₂, CO, O₃ and PM₁₀ in Ahvaz in the period of 10 years (2007–2017). Data on referrals and the number of hospitalized cardiovascular and respiratory patients and also on air pollutants are obtained through Hospital Information System and air quality monitoring stations including Department of Environment Protection Station, Naderi Square Station, University Square Station and the Meteorological Organization Station. The data were analyzed by SPSS version 4 and Poisson distribution regression model to evaluate the effects of each pollutant and the rate of hospitalization. In this study, confidence interval and the significance level are considered at 95% and 5%, respectively. Changes in air pollution indices and number of patients with cardiovascular diseases were evaluated using Excel, Stata and ARIMA models. Based on the results of Poisson regression analysis, there was a significant relationship between the average concentration of NO₂, O₃, CO and SO₂ and hospitalization of patients with cardiovascular disease, with a confidence level of less than 5%. This was the case with NO₂ more than other pollutants. Furthermore, there was a significant relationship between the average concentrations of NO₂, CO and O₃ and the hospitalization rate of patients with respiratory problems and a confidence level of 5%. The effect of NO₂ was also higher here. Due to the results, NO₂, CO, and O₃ had a significant direct correlation with cardiovascular and respiratory rates. The effect of NO₂ has been higher than other pollutants. In the study of time intervals of patients with cardiovascular, the results of time-interval analysis indicate the relationship between cardiovascular clients with the "t" time of 7 days earlier and NO₂ as a pollutant. The results of this analysis also revealed the relationship between respiratory patients at the time "t" up to 7 days before and O₃.