| Summary: | In present China, continuing to control PM<sub>2.5</sub> (particulate matter < 2.5 μm) and preventing the rise of O<sub>3</sub> are the most urgent environmental tasks in its air clean actions. Considering that NO<sub>2</sub> is an important precursor of PM<sub>2.5</sub> and O<sub>3</sub>, a comprehensive analysis around this pollutant was conducted based on the real-time-monitoring data from Jan 2018 to Mar 2019 in 11 prefecture-level cities in Shanxi Province of China. The results showed that the annual average concentration of NO<sub>2</sub> in Shanxi prefecture-level cities is mainly distributed in the range of 28.84–48.93 μg/m<sup>3</sup> with the values in five cities exceeding the Chinese Grade Ⅱ standard limit (40 μg/m<sup>3</sup>). The over-standard days were all concentrated in the heating season with a large pollution peak occurring in winter except in Lvliang, while four cities also had a small pollution peak in summer. High NO<sub>2</sub> polluted areas were mainly concentrated in the central part of Shanxi, and trended on the whole from the southwest to the northeast (Lvliang/Linfen—Taiyuan/Jinzhong—Yangquan/Jinzhong), which was different from the spatial distribution of PM<sub>2.5</sub> and O<sub>3</sub>. Lvliang was the hot spot of NO<sub>2</sub> pollution in summer, while Taiyuan was the hot spot in winter. Concentration Weighted Trajectory (CWT) analysis indicated that central-north Shaanxi, central-south Shanxi, northern Henan, the south of Shijiazhuang and areas around Erdos in Inner Mongolia were important source areas of NO<sub>2</sub> in Shanxi besides local emissions. Our findings are expected to provide valuable implications to policymakers in Shanxi of China to effectively abate the air pollution.
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