Median Air Quality Index
The Air Quality Index on the middle day of the year: half the days had cleaner air and half had dirtier air. The index runs from 0 to 500 and is set by the worst pollutant that day. Under 50 is good. Over 100 is unhealthy for sensitive groups, such as children and people with asthma. It comes from air monitors, so only about 800 counties have it. A county with no value has no monitor, not clean air. A year counts only if the monitors gave a reading on at least 274 days.
Reported for803areas, in 51 states — none in CT
Link to density0.36not mostly about how urban a place is
Nearby places alike0.25Moran’s I: only weakly, little map pattern
TyperateAQI
How it has moved
Loading…
Every state, every year
Nothing to draw here: this measure has no state figures. Its publisher reports it for counties. This site does not add county numbers up into state figures, since a home-made figure could clash with one an agency publishes itself. The chart above covers the whole country, year by year.
Where it comes from
EPA Air Quality System · EPA AQS annual_aqi_by_county, Median AQI
The middle day's AQI: half of the year's measured days were cleaner and half dirtier. A middle value cannot be built from smaller areas. Only counties with an air monitor, about 800 a year lately, and only years with an AQI on at least 274 days.
Combining areas: it cannot be combined, so it is shown only where its publisher works it out.
What it goes with
The strongest links that have a page of their own. Unadjusted is the link before adjusting for anything, from −1 (opposite) to +1 (in step). Adjusted compares places with the same population density, income and education levels, so those differences can’t explain the link. This list leaves out the 2 pairs built from the same numbers or the same model as this measure, since they are bound to match.
| Measure | Unadjusted | Adjusted |
|---|---|---|
| Median Air Quality Index and Population (WONDER)Where Median Air Quality Index is higher, Population (WONDER) tends to be higher: a weak link that holds when only places with similar density, income and education are compared. Population (WONDER) by US county | +0.37 | +0.39 |
Population makeup
How this measure varies with the racial and ethnic makeup of counties. Every group is shown, whatever its rank. These are links across counties: they describe places, not people. They say nothing about any person’s risk or behaviour based on their race. Counties with a larger share of one group also differ in much else, such as income, segregation, region and history. The adjusted figure only accounts for density, income and education.
| Share of residents | Unadjusted | Adjusted |
|---|---|---|
| Median Air Quality Index and Share White, not HispanicCould easily be chance once only places with similar density, income and education are compared. Share White, not Hispanic by US county | -0.20 | -0.06 |
| Median Air Quality Index and Share Black, not HispanicCould easily be chance once only places with similar density, income and education are compared. Share Black, not Hispanic by US county | +0.23 | +0.06 |
| Median Air Quality Index and Share Hispanic or Latino, any raceCould easily be chance once only places with similar density, income and education are compared. Share Hispanic or Latino, any race by US county | +0.08 | +0.04 |
| Median Air Quality Index and Share Asian, not HispanicCould easily be chance once only places with similar density, income and education are compared. Share Asian, not Hispanic by US county | +0.07 | -0.01 |
| Median Air Quality Index and Share American Indian or Alaska Native, not HispanicCould easily be chance once only places with similar density, income and education are compared. Share American Indian or Alaska Native, not Hispanic by US county | -0.19 | -0.09 |
Highest and lowest
Of 803 counties reporting it. These are the two ends of a national ranking. For most measures, that ranking mostly sorts places by income and how urban they are. That is why the place pages compare each place with similar places instead.
Highest
- Riverside County, CA — 77
- Maricopa County, AZ — 72
- San Bernardino County, CA — 71
- Tulare County, CA — 69
- Kern County, CA — 69
Lowest
The middle area reports 43. The middle half of counties falls between 38 and 48 (the 25th to 75th percentile).
US Counties With the Highest Median Air Quality Index · US Counties With the Lowest Median Air Quality Index
All measures · Explore its pairs · How the US county data works