Temperature modification of air pollutants and their synergistic effects on respiratory diseases in a semi-arid city in Northwest China

Air pollutants and temperature are significant threats to public health, and the complex linkages between the environmental factors and their interactions harm respiratory diseases. This study is aimed to analyze the impact of air pollutants and meteorological factors on respiratory diseases and their synergistic effects in Dingxi, a city in northwestern China, from 2018 to 2020 using a generalized additive model (GAM). Relative risk (RR) was employed to quantitatively evaluate the temperature modification on the short-term effects of PM 2.5 and O 3 and the synergistic effects of air pollutants (PM 2.5 and O 3 ) and meteorological elements (temperature and relative humidity) on respiratory diseases. The results indicated that the RRs per inter-quatile range (IQR) rise in PM 2.5 and O 3 concentrations were (1.066, 95% CI: 1.009–1.127, lag2) and (1.037, 95% CI: 0.975–1.102, lag4) for respiratory diseases, respectively. Temperature stratification suggests that the influence of PM 2.5 on respiratory diseases was significantly enhanced at low and moderate temperatures, and the risk of respiratory diseases caused by O 3 was significantly increased at high temperatures. The synergy analysis demonstrated significant a synergistic effect of PM 2.5 with low temperature and high relative humidity and an antagonistic effect of high relative humidity and O 3 on respiratory diseases. The findings would provide a scientific basis for the impact of pollutants on respiratory diseases in Northwest China.