Annual EPA record

US Air Quality Trends: Annual EPA AQI Data, 2020–2025

A historical view of annual EPA Air Quality System summaries, not a current-air report. It compares the unweighted Good-day share across monitored counties. For current conditions and alerts, use AirNow.

Latest annual record 76% Good-day share in 2025

What these annual summaries show

  • 1.The county-average Good-day share was 77.7% in 2020 and 76% in 2025, a -1.7 percentage-point difference.
  • 2.The lowest value in this six-year series was 69.6% in 2023; it is an annual aggregate, not a measure of any one event or cause.
  • 3.The highest value was 77.7% in 2020. Use the county and metro profiles to see how individual places differ from the national county average.

National Good-day share by year

Unweighted average county share of monitored days rated Good (AQI 0–50)

  1. 1 2020 77.7%
  2. 2 2021 72%
  3. 3 2022 75.1%
  4. 4 2023 69.6%
  5. 5 2024 75.4%
  6. 6 2025 76%

Good-day share · EPA Air Quality System, county_trends 2020–2025

EPA Air Quality System (AQS), annual county summaries 2020–2025. This descriptive series does not assign causes to year-to-year changes.

Release-to-release report

What changed in the retained 2020-2025 county record

-1.3pp average county change

Among 864 counties monitored at least 200 days in both endpoint years, 303 recorded a Good-day share at least one percentage point higher and 488 recorded a share at least one point lower. The average county change was -1.3 percentage points.

These are descriptive comparisons of two annual EPA releases, not an attribution of cause or a current-air forecast. Review the adjacent-release change report, the county improvement ranking, the county decline ranking, or compare two places directly with the county comparison tool.

Cleanest states by Good-day share

Latest annual share of Good air days

  1. 1 Hawaii 93.8%
  2. 2 Maine 87%
  3. 3 Virginia 86.5%
  4. 4 Montana 85.9%
  5. 5 Wyoming 85.1%
  6. 6 Nebraska 85%
  7. 7 New Hampshire 84.9%
  8. 8 Alaska 84.4%
  9. 9 Puerto Rico 84%
  10. 10 Vermont 83.8%

Good-day share · EPA Air Quality System

States with the highest average AQI

Latest annual median AQI; higher values indicate worse annual conditions

  1. 1 California 46
  2. 2 District of Columbia 45
  3. 3 Arizona 45
  4. 4 Arkansas 45
  5. 5 Georgia 43
  6. 6 Oklahoma 43
  7. 7 Ohio 43
  8. 8 South Carolina 43
  9. 9 Iowa 42
  10. 10 Utah 42

Avg median AQI · EPA Air Quality System

EPA Air Quality System (AQS) annual county summaries, 2025. State figures aggregate every monitored county within the state.

How to read this annual history

Each point is built from county-level EPA annual summaries. The chart averages county percentages equally, so it describes the typical monitored county in this dataset rather than a population-weighted national exposure estimate. A county can also change because its monitoring coverage or weather differs from the prior year.

The series is useful for comparing annual records, but it cannot establish why a change occurred. It does not replace a current-air alert, a source-specific pollution analysis, or a health assessment.

Use a county profile or metro profile to compare the underlying annual records for a particular geography. The data source uses CBSA geography for metro records, so metro results are not labelled as city measurements.

Compare change directly

The county improvement ranking compares Good-day share in 2020 and 2025, with a 200-monitored-day floor in both years. That avoids treating a simple change in the number of monitored days as an air-quality improvement.

A change in this ranking is a descriptive difference between the two annual records. It is not a finding about the cause of the change, a forecast, or a current-condition rating.

Data source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), annual summary files (2020-2025).

Data vintage: 2025 is the most recent complete annual record in this series.