To investigate the spatiotemporal patterns law of PM2.5 pollution in China, statistical methods and GIS technology were used to analyze the ground-level PM2.5 monitoring results in 2014 from 161 cities at or above prefectural level in national air quality monitoring network. The results showed that only 8.1% cities met Grade II standard of ambient air quality standards (GB 3095~2012), and about 26.6% days failed to meet Grade II air quality standards. Diurnal PM2.5 pollution was least in summer, late spring and early autumn, and was heavy in winter. Daily PM2.5 concentration followed an indistinctive bimodal curve with minimum value around 16:00 and maximum value around 10:00. The pollution levels were relatively high from midnight to dawn. PM2.5 pollution was serious in Beijing-Tianjin-Hebei region and its surrounding area, as well as Hubei, Hunan and Anhui. PM2.5 pollution was least in southeast coast and Yunnan, Tibet. The spatial distribution of PM2.5 was significantly correlated with spatial distributions of wind speed, relative humidity, and land use. The average ratio of PM2.5 in PM10 (PM2.5/PM10 ratio) was 0.591, which has spatial pattern of gradually increasing from northwest to southeast, and was higher in south region than in north region. Monthly average PM2.5/PM10 ratio was basically stable ranged in 0.55~0.6, excluding higher in January, February, and lower in May. The results could benefit to further understanding on the spatiotemporal patterns of PM2.5 pollution in China macroscopically, and promote to environmental pollution prevention and control measures accordingly.
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