[Spatio-temporal Evolution and Population Exposure Risk to PM_2.5 in the Guanzhong Area]

In recent years, atmospheric pollution represented by fine particulate matter PM_2.5 pollution has seriously threatened human health. Therefore, it is important to identify the risk level of population exposure to PM_2.5. Based on PM_2.5 remote sensing inversion data and population distribution, this study measured the risk level of population exposure to PM_2.5 in the Guanzhong area. Furthermore, the methods of Theil-Sen Median trend analysis, Mann-Kendall test, and geo-spatial analysis were used to reveal the temporal and spatial characteristics of population exposures risk to PM_2.5 in the Guanzhong area from 2000 to 2016. The results show that:①The years with heavy pollution and wide range in the Guanzhong area are 2006, 2007, and 2013, and the annual average concentration of PM_2.5 exceeded 35 μg·m^-3 in more than 40% of the Guanzhong area. From 2000 to 2016, the spatial distribution range of PM_2.5 in the Guanzhong area continued to expand, forming a continuous belt-shaped concentrated distribution area from the center to the northeast. ②More than 60% of the population in the Guanzhong area was exposed in the areas with annual average concentration of PM_2.5 above 35 μg·m^-3 from 2000 to 2016, and the population exposure risk continued to increase, especially after 2011, the range of the high-risk area expanded dramatically. ③The pattern of population exposure risk to PM_2.5 in the Guanzhong area was generally similar from 2000 to 2016. The areas with higher risk levels were mainly concentrated in the central Guanzhong area, forming a continuous belt-shaped distribution area from west to east. The areas with the highest value were distributed in the urban areas of several major cities, while the areas with the lowest value were mainly concentrated in the surrounding areas of Guanzhong.