Trends and drivers of anthropogenic NO emissions in China since 2020

Nitrogen oxides (NO x ), significant contributors to air pollution and climate change, form aerosols and ozone in the atmosphere. Accurate, timely, and transparent information on NO x emissions is essential for decision-making to mitigate both haze and ozone pollution. However, a comprehensive understanding of the trends and drivers behind anthropogenic NO x emissions from China—the world's largest emitter—has been lacking since 2020 due to delays in emissions reporting. Here we show a consistent decline in China's NO x emissions from 2020 to 2022, despite increased fossil fuel consumption, utilizing satellite observations as constraints for NO x emission estimates through atmospheric inversion. This reduction is corroborated by data from two independent spaceborne instruments: the TROPOspheric Monitoring Instrument (TROPOMI) and the Ozone Monitoring Instrument (OMI). Notably, a reduction in transport emissions, largely due to the COVID-19 lockdowns, slightly decreased China's NO x emissions in 2020. In subsequent years, 2021 and 2022, reductions in NO x emissions were driven by the industry and transport sectors, influenced by stringent air pollution controls. The satellite-based inversion system developed in this study represents a significant advancement in the real-time monitoring of regional air pollution emissions from space. • We integrate top-down inversion with bottom-up information to infer NO x emissions. • China's monthly and sectoral NO x emissions are estimated from 2020 to 2022. • China's NO x emissions have declined since 2020 despite increased fuel consumption. • Air pollution control led to widespread emission declines in 2021 and 2022.