*Article* **Regional Air Pollutant Characteristics and Health Risk Assessment of Large Cities in Northeast China**

**Chunsheng Fang, Hanbo Gao, Zhuoqiong Li and Ju Wang \***

College of New Energy and Environment, Jilin University, Changchun 130012, China; fangcs@jlu.edu.cn (C.F.); gaohb19@mails.jlu.edu.cn (H.G.); zhuoqiong21@mails.jlu.edu.cn (Z.L.) **\*** Correspondence: wangju@jlu.edu.cn; Tel.: +86-131-0431-7228

**Abstract:** This study systematically investigated the pollution characteristics of atmospheric O3 and PM2.5, regional transport, and their health risks in three provincial capitals in northeast China during 2016–2020. The results show that O3 concentrations showed a trend of high summer and low winter, while PM2.5 concentrations showed a trend of high winter and low summer during these five years. The results of the correlation analysis indicate that external sources contribute more O3, while PM2.5 is more from local sources. The backward trajectory clustering analysis results showed that Changchun had the highest share of northwest trajectory with a five-year average value of 67.89%, and the city with the highest percentage of southwest trajectory was Shenyang with a five-year average value of 23.95%. The backward trajectory clustering analysis results showed that the share of the northwest trajectory decreased and the share of the southwest trajectory increased for all three cities in 2020 compared to 2016. The results of the potential source contribution function (PSCF) and concentration weighting trajectory (CWT) analysis showed that the main potential source areas and high concentration contribution areas for PM2.5 in the northeast were concentrated in Mongolia, Inner Mongolia, Shandong Province, and the northeast, and for O3 were mainly located in Shandong, Anhui, and Jiangsu Provinces, and the Yellow Sea and Bohai Sea. The non-carcinogenic risk of PM2.5 in Harbin was high with a HQ of 2.04, while the other cities were at acceptable levels (HQ < 0.69) and the non-carcinogenic risk of O3 was acceptable in all three cities (HQ < 0.22). However, PM2.5 had a high carcinogenic risk (4 × 10−<sup>4</sup> < CR < 0.44) and further treatment is needed to reduce the risk.

**Keywords:** PM2.5; ozone; cluster analysis; health risk
