Where is measured air quality best, and worst?
Across counties with a sustained federal air-monitoring record, which have the lowest and highest day-weighted mean Air Quality Index?
What this study shows
A ranking of counties by day-weighted mean AQI, with the number of monitored days behind each figure and the count of days unhealthy for sensitive groups.
What it cannot show
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.
Computing this study from released data…
Sources
- EPA AirData daily AQI by county (air_quality_months)
Association is not causation: co-occurrence in the same county does not show that any exposure caused any outcome.
Definitions, suppression rules and reproducibility are documented in Methods.