Association and interaction of O(3) and NO(2) with emergency room visits for respiratory diseases in Beijing, China: a time-series study

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. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-022-14473-2.