Relationship of Air Pollution and Daily Hospital Admissions Due to Respiratory Disease: A Time Series Analysis

Air pollutants and respiratory diseases have a significant relationship and cause major health problems. Low attention has been paid to the daily hospital admissions due to the presence of pollutants in desert cities such as Yazd city, Iran. Therefore, this study aimed to investigate the short-term relationship between air pollution and daily hospital admissions due to respiratory disease in Yazd hospitals.

This cross-sectional study investigated pollutants including PM10, CO, SO2, NO2, and O3 recorded daily in Yazd air pollution monitoring station. Moreover, the daily hospital admissions (sample size =180) of the pulmonary patients were collected from government hospitals from March to September 2017. 

The results showed that PM10 concentrations were higher than the Environmental Protection Agency (EPA) and World Health Organization standards. Furthermore, only 7.6% of the patients' diseases were attributed to air pollution. The highest correlation (R = 0.595 and P = 0.002) was observed between daily hospital admissions and NO2 concentration. However, after age adjustment in regression analysis, this relationship was also significant for O3. The behavior and variations of pollutants were interpreted by time series using auto-regressive moving average (ARMA) (1,1). The results showed that the best correlation was found between pollutants and admission of the patients at lag = 48 hr. 

The daily admission of patients to hospital due to pulmonary disease was highly related to NO2 and O3. However, the correlation of admission with CO, PM10, and SO2 was not significant, because NO2 and O3 are oxidation factors and stimulate the respiratory system.