Association and interaction of O3 and NO2 with emergency room visits for respiratory diseases in Beijing, China: a time-series study

Abstract

Abstract Background Ozone (O 3 ) and nitrogen dioxide (NO 2 ) are the two main gaseous pollutants in the atmosphere that act as oxidants. Their short-term effects and interaction on emergency room visits (ERVs) for respiratory diseases remain unclear. Methods We conducted a time-series study based on 144,326 ERVs for respiratory diseases of Peking University Third Hospital from 2014 to 2019 in Beijing, China. Generalized additive models with quasi-Poisson regression were performed to analyze the association of O 3 , NO 2 and their composite indicators (O x and O x wt ) with ERVs for respiratory diseases. An interaction model was further performed to evaluate the interaction between O 3 and NO 2 . Results Exposure to O 3 , NO 2 , O x and O x wt was positively associated with ERVs for total respiratory diseases and acute upper respiratory infection (AURI). For instance, a 10 μg/m 3 increase in O 3 and NO 2 were associated with 0.93% (95%CI: 0.05%, 1.81%) and 5.87% (95%CI: 3.92%, 7.85%) increase in AURI at lag0-5 days, respectively. Significant linear exposure–response relationships were observed in O x and O x wt over the entire concentration range. In stratification analysis, stronger associations were observed in the group aged < 18 years for both O 3 and NO 2 , in the warm season for O 3 , but in the cold season for NO 2 . In interaction analysis, the effect of O 3 on total respiratory emergency room visits and AURI visits was the strongest at high levels (> 75% quantile) of NO 2 in the < 18 years group. Conclusions Short-term exposure to O 3 and NO 2 was positively associated with ERVs for respiratory diseases, particularly in younger people (< 18 years). This study for the first time demonstrated the synergistic effect of O 3 and NO 2 on respiratory ERVs, and O x and O x wt may be potential proxies.

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