Spatial and temporal variation of PM 2.5 and PM 10 in cities in China from 2016 to 2018

Abstract

Abstract Particulate matter pollution is the cause of many diseases and the focus of urban atmospheric environmental research. Here, the spatiotemporal variations of PM2.5 and PM10 concentrations were analyzed across 71 cities in China using spatiotemporal sequence analyses and spatial interpolation of national monitoring data collected between 2016 and 2018. Significant differences were observed in the spatiotemporal variations of PM2.5 and PM10 concentrations across the country. PM2.5 concentrations in winter, spring, autumn, and summer were 60.16, 41.95, 37.10, and 26.94 µg/m3, respectively. The PM10 concentrations in spring and winter exhibited little difference at 89.50 and 92.30 µg/m3, respectively, but were higher than values observed in autumn and summer. The national annual average PM2.5 concentration decreased from 44.94 µg/m3 in 2016 to 37.75 µg/m3 in 2018, while that of PM10 decreased from 80.42 to 70.14 µg/m3. From 2016 to 2018, the monthly average concentrations of PM2.5 and PM10 in the 71 cities generally showed a downward trend. The average PM2.5 concentration in May comprised a single yearly peak, while the average PM10 concentration in October exhibited a second peak. The national PM2.5 and PM10 concentrations began to rise in September and October of each year and then decline in March and April of the next year. Spatial variation analysis revealed that the Hu Huanyong line is the east-west boundary line differentiating China's PM2.5 and PM10 concentrations (excluding Xinjiang), while the Yangtze River is the north-south boundary line. High pollution areas were mainly distributed in fast-growing urban agglomerations for instance the Central Plains, Bohai, and Yangtze River Delta urban agglomerations, in addition to the Xinjiang region. The annual average PM2.5 mass concentrations across the seven geographic regions of China followed the order of Central > North > Northwest > Northeast > East > Southwest > South China. Further, the annual average PM10 mass concentration followed the order of Northwest > Central > North > Northeast > North > Southwest > South China. From a spatial perspective, the PM2.5 and PM10 concentrations began to rise in September and October every year, then gradually spread outward from the Shandong, Shanxi, Henan, and Hebei provinces. The monthly increases comprised about 10–20 µg/m3, while the PM2.5 average concentration in most areas south of the Yangtze River exceeded 60 µg/m3 in May. Further, from March and April of the next year, a high-value area centered around Henan began to gradually decrease, and the division of concentrations between the north and south via the Yangtze River became more obvious.