Health risk assessment of NO₂ exposure on respiratory outpatient visits in the North China Plain during wintertime

Nitrogen dioxide (NO₂) exposure has rarely been explored with respiratory outpatient visits in China. The Generalized Additive Model (GAM) is first employed to assess health related risk (RR) with NO₂ and PM_2.5 exposure in Tianjin during the winter of 2019/2020. The RR of NO₂ exposure is 1.018 (95 % CI: 1.012–1.024) on lag 3 days, while that of fine particulate matter (PM_2.5) exposure is 1.005 (95 % CI: 1.002–1.008) on lag 4 days per 10 μg m⁻³. The Weather Research and Forecasting model coupled to Chemistry (WRF-Chem) model is used to simulate the pollutant concentrations to calculate the total number of excess visits (EN) in the North China Plain (NCP) in the 2019/2020 winter. The EN of NO₂ exposure is 0.97 million (95 % CI: 0.67, 1.27), while for PM_2.5 exposure is 1.19 million (95 % CI: 0.50, 1.84). With the anthropogenic emission mitigation, the PM_2.5 concentration has dropped by 40.3 μg m⁻³ on average in the NCP, but the NO₂ concentration has rebounded by 1.8 μg m⁻³. The emissions mitigation reduces NO₂-related EN by 0.76 million (95 % CI: 0.53–0.98) and PM_2.5-related EN by 1.11 million (95 % CI: 0.48–1.69). The findings underscore that reducing NO₂ emissions could yield more substantial health benefits.