Abstract
Particulate Matter (PM) is an important indicator of the degree of air pollution. The PM type and the ratio of coarse and fine PM particles determine the ability to affect human health and atmospheric processes. Using the observation data across the country from 2015 to 2018, this study investigates the distribution and proportion of PM2.5 and PM10 at different temporal and spatial scales in mainland China; clarifies the PM2.5, PM10 and PM2.5/PM10 ratios interrelation; and classifies the dust, mixed, and anthropogenic type aerosol. It shows that the annual average concentration of PM2.5 and PM10 decreased by 10.55 and 8.78 μg m−3 in 4 years. PM2.5, PM10, and PM2.5/PM10 ratios show obvious while different seasonal variations. PM2.5 is high in winter and low in summer, while PM10 is high in winter and spring, and low in summer and autumn. Differently, the PM2.5/PM10 ratios are the highest in winter, and the lowest in spring. PM2.5/PM10 ratios show strong independence on PM2.5 and PM10, implying that it can provide extra information about the aerosol pollution such as aerosol type. A classification method about air pollution types is then further proposed based on probability distribution function (PDF) morphology of PM2.5/PM10 ratios. The results show that dust type mainly lies in the west of Hu-Line, mixed type pollution distributes near Hu-Line, and the anthropogenic type dominates over North China Plain and cities in southern China. The results provide insights into China’s future clean air policy making and environmental research.
Highlights
Due to its severe impact on human health and significant atmospheric visibility reduction, Particulate Matter (PM) has attracted increasing attention worldwide (Lelieveld et al, 2015; GuVariations of the PM2.5/PM10 Ratios et al, 2016; An et al, 2019; Zhang et al, 2019; Zhao et al, 2020)
In order to fully understand the changes of air pollution in China and make reliable policies to control air pollution, this study aims to quantify the PM2.5, PM10, PM2.5/PM10 ratios by using the ground observation data from 367 cities across the country between 2015 and 2018, to reveal their differences in spatial and temporal changes, and to propose a method to classify the air pollution types over various regions based on PM2.5/PM10 ratios
Same as the findings from previous studies (Wang et al, 2015; Zhang et al, 2019; Fan et al, 2020), PM2.5 has been the focus of air pollution control since 2013, so the rate of its decline has been faster than other air pollutants
Summary
Due to its severe impact on human health and significant atmospheric visibility reduction, Particulate Matter (PM) has attracted increasing attention worldwide (Lelieveld et al, 2015; GuVariations of the PM2.5/PM10 Ratios et al, 2016; An et al, 2019; Zhang et al, 2019; Zhao et al, 2020). Associated with the different meteorological conditions, the size and composition of PM in the atmosphere vary widely, and could cause various health hazards and weather and climate effects over different locations (Huang et al, 2014; Lelieveld et al, 2015; Liao et al, 2015; Wang et al, 2015; Zhao et al, 2017). Particles between 2.5 and 10 μm are mainly from natural sources, such as desert, while they may be caused by human activities, such as road dust and industrial emissions (Gu et al, 2016; Zhou et al, 2016; Chen et al, 2017; Tian et al, 2018). Understanding the proportion of fine particles in the atmosphere is important for air pollution control and related researches
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