US Counties With the Highest Days with an Air Quality Reading
803 US counties ranked by days with an air quality reading, from highest to lowest. First are New Castle County, DE (365), Sussex County, DE (365) and District of Columbia, DC (365). The middle one of the 803 has 365.
What this measures
How many days of the year the county's air monitors gave an Air Quality Index reading. It shows how well the county's air is watched, not how clean it is. Counties with no monitor are missing. Years with fewer than 274 days are left out of the air measures, since part of a year can't be compared with a whole one. Source: EPA Air Quality System.
For most measures, a national ranking mostly sorts places by income and by how urban they are. Each county’s own page compares it with the 50 counties most like it instead, which is often the fairer view.
The 100 highest counties
More on days with an air quality reading
- US Counties With the Lowest Days with an Air Quality Reading
- Days with an air quality reading by US county: map by year and what it goes with
A ranking describes places, not the people in them, and a high or low place does not by itself say why. All US rankings.