Abstract: This article mainly analyze urban air quality present situation in China and the key factors affecting urban air quality study.

摘要：本文针对我国城市的空气质量现状及影响城市空气质量的主要因素进行分析研究。

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The American Lung Association's study ranks the air quality of 900 counties and more than 200 U.S. Census-defined Metropolitan Statistical Areas and Combined Statistical Areas--cities and their surrounding suburbs--where an air pollution monitor is present.

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They included physicians per capita, air quality, quality-of-aging metrics drawn from another Milken Institute study, and crime rates.

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The insight comes from a study looking at London's air quality records.

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