Each study below is computed when you open it, from the same released public data the map uses. Every one states what it can show and what it cannot. None of them establishes that anything caused an outcome.
Across counties with a sustained federal air-monitoring record, which have the lowest and highest day-weighted mean Air Quality Index?
What this cannot answer: Only counties with a monitor are ranked. A county with no monitor is absent from this study, not clean. Monitor placement, terrain and seasonality all shape a county's mean.
Read the studyGrouping monitored counties into quartiles of day-weighted mean AQI, what is the published all-cause infant mortality rate in each quartile?
What this cannot answer: This is an ecological comparison of areas, not of people. It cannot show that air quality caused any outcome, and it is not adjusted for social, economic or clinical differences between counties.
Read the studyUsing the published EPA county Environmental Quality Index, which counties sit at each end of the national distribution?
What this cannot answer: The index is a composite of historic domain measures for 2006–2010. It describes county conditions over that period and says nothing about an individual's exposure or about any health outcome.
Read the study