Period, a decreasing trend was observed for the annual average concentration of PM 2.5, especially at sampling sites in layer 1, where the stricter control policies were implemented. Urbanization levels had a strong effect on air quality. The PM 2.5 composition of layer 3 in 2019 was found to be similar to that of the other layers 2 or 3 years ago, implying that Spatial clustering of the chemical composition at the sampling sites was conducted for each The average PM 2.5 concentrations for 5 years were in the order of Layer 3 belonged to the outermost zone with the lowest urbanization level.

Zone of Chengdu, layer 2 was located in the outer circle of layer 1, and Layer 1 was the most urbanized area and referred to the core Total of 836 samples were collected from 19 sites in winter 2015–2019.Īccording to the specific characteristics, 19 sampling sites were assigned Investigate the spatiotemporal and policy-related variations of PM 2.5Ĭomposition and sources based on long-term observation at multiple sites. Rapidly developing Chinese megacity, Chengdu, as the study area to Study health effects and improve air quality. A thorough understanding of the relationship between urbanizationĪnd PM 2.5 (fine particulate matter with aerodynamic diameter less thanĢ.5 µm) variation is crucial for researchers and policymakers to

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