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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The health impacts valuations presented in the study come from national benefit per ton figures developed from a Community Multi-scale Air Quality (CMAQ) model, which is regularly used in EPA Clean Air Act rulemaking.

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The study by Wiltshire Wildlife Trust (WWT) and Wiltshire Council measured housing figures, carbon emissions, air quality and biodiversity.

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The study was actually conducted in and reported on air pollution in Boston, but it pointed out that air quality levels even below current standards set by the Environmental Protection Agency still pose risks to people who breathe particulate air pollution.

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