Temporal and Spatial Distribution Analysis of Atmospheric Pollutants in Chengdu-Chongqing Twin-City Economic Circle

In order to study the temporal and spatial distribution characteristics of atmospheric pollutants in cities (districts and counties) in the Chengdu-Chongqing Twin-city Economic Circle (CCEC) and to provide a theoretical basis for atmospheric pollution prevention and control, this paper combined Ambient Air Quality Standards (AAQS) and WHO Global Air Quality Guidelines (GAQG) to evaluate atmospheric pollution and used spatial correlation to determine key pollution areas. The results showed that the distribution of atmospheric pollutants in CCEC presents a certain law, which was consistent with the air pollution transmission channels. Except for particulate matter with an aerodynamic diameter equal to or less than 2.5 μm (PM_2.5) and ozone (O₃), other pollutants reached Grade II of AAQS in 2020, among which particulate matter with an aerodynamic diameter equal to or less than 10 μm (PM₁₀), PM_2.5, sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and carbon monoxide (CO) have improved. Compared with the air quality guidelines given in the GAQG, PM₁₀, PM_2.5, NO₂ and O₃ have certain effects on human health. The spatial aggregation of PM₁₀ and PM_2.5 decreased year by year, while the spatial aggregation of O₃ increased with the change in time, and the distribution of NO₂ pollution had no obvious aggregation. Comprehensive analysis showed that the pollution problems of particulate matter, NO₂ and O₃ in CCEC need to be further controlled.