Ground-level gaseous pollutants (NO₂, SO₂, and CO) in China: daily seamless mapping and spatiotemporal variations

Abstract. Gaseous pollutants at the ground level seriously threaten urban air quality environment and public health. There are few estimates of gaseous that spatially temporally resolved continuous across China. This study takes advantage big data artificial-intelligence technologies to generate seamless daily maps three major ambient pollutant gases, i.e., NO2, SO2, CO, China from 2013 2020 a uniform spatial resolution 10 km. Cross-validation between our observations illustrated high on basis for surface CO concentrations, with mean coefficients determination (root-mean-square errors) 0.84 (7.99 µg m−3), (10.7 0.80 (0.29 mg respectively. We found COVID-19 lockdown had sustained impacts pollutants, where recovered its normal in around 34th day after Lunar New Year, while SO2 NO2 rebounded more than 2 times slower due emissions residents' increased indoor cooking atmospheric oxidation capacity. Surface reached their peak annual concentrations 21.3 ± 8.8 m−3, 23.1 13.3 1.01 0.29 m−3 2013, then continuously declined over time by 12 %, 55 17 respectively, until 2020. The declining rates were prominent 2017 sharper reductions anthropogenic but have slowed down recent years. Nevertheless, people still suffer high-frequency risk exposure eastern China, almost World Health Organization (WHO) recommended short-term guidelines (AQG) since 2018, benefiting implemented stricter “ultra-low” emission standards. reconstructed dataset will benefit future (especially short-term) pollution environmental health-related studies.