Spatial and temporal variation characteristics of air pollutants in Xi'an during 2017-2020 / 公共卫生与预防医学

ABSTRACT

Objective To analyze the temporal and spatial variation characteristics of six common air pollutants in Xi'an, and to provide a scientific basis for the environmental protection departments to conduct targeted prevention and control. Methods Based on air pollution monitoring data with high temporal resolution, the temporal and spatial distribution characteristics of six common air pollutants in Xi'an were analyzed, and the correlation between the pollutants was studied. Results Except for O3_8h, the annual average concentrations of the other five air pollutants decreased year by year. By 2020, the annual average concentration of PM2.5 and PM10 still exceeded the second-level concentration limit. The annual average concentration of NO2 was slightly higher than the first-level concentration limit, and the number of unqualified days of O3_8h accounted for one-tenth of the entire year. The concentrations of PM2.5, PM10, CO, SO2, and NO2 all were the highest in winter, equivalent in spring and autumn, and the lowest in summer. The concentration of O3_8h generally presented the characteristics of summer > spring > autumn > winter. In 2020, the annual average concentrations of PM2.5 and PM10 in 9 urban areas exceeded the second-level concentration limit. The annual average concentrations of NO2 in Xincheng District, Lianhu District, Beilin District, and Yanta District all exceeded the second-level concentration limit. The annual average concentration of O3_8h in Beilin District, Chang'an District, and Yanliang District all exceeded the average level of Xi'an. PM2.5, PM10, CO, SO2, and NO2 in general showed a positive correlation in varying degrees. In summer, O3_8h showed a positive correlation with other air pollutants, but a negative correlation in other seasons. Conclusion The air pollution situation in Xi'an has been improving year by year, but the pollution of PM2.5, PM10, and O3_8h still exceeds the standard, which will be the focus of long-term prevention and control of air pollution in Xi'an.