National ranking · cleanest air

Best Air Quality in the US (2025)

Ranked by the highest share of Good air days among counties with at least 100 monitored days in 2025, the counties where residents breathe the cleanest air most often, from EPA Air Quality System monitoring.

97.3%
#1 Claiborne, Tennessee
23
Counties ranked

Claiborne County, Tennessee leads the 2025 cleanest-air list among 23 ranked U.S. counties (97.3% Good)

According to the U.S. EPA Air Quality System, this ranking orders 23 counties with at least 100 monitored days in 2025 by the highest share of days in the Good AQI band, using median AQI to separate near-ties. It describes a historical reporting year, not today's air quality. For current conditions and alerts, use AirNow.

Data source EPA Air Quality System (AQS)

#1 Good-day share
Claiborne County, Tennessee ranks #1 of 23 for Good-day share at 97.3%.
#1 median AQI
#1 median AQI: 35
Counties ranked
Counties ranked: 23
Tied at 100% Good
Tied at 100% Good: 0

from the compiled EPA AQS release in this database.

Counties below the 100-day monitoring floor are excluded: with only a handful of readings, a single clean stretch can push a county to a 100% Good-day rate that a normal year's weather would not hold up. 0 counties tie at 100.0% with this floor applied, all with a genuinely large sample of monitored days. For comparison, the cohort median across all 951 floor-qualifying counties is 77.5%, meaning the difference between a top-ranked county and a typical monitored county is real, not sampling noise.

Filter this ranking

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Filters keep the Good-day-share ranking contract. A state filter ranks that state's qualifying counties; pollutant filters keep rows whose annual day-type count is led by ozone, PM2.5, or PM10. Raising the monitored-days floor tightens the sample beyond the default 100-day Module-34 guard.

Compare up to three counties

Showing 23 matching Tennessee counties . Back to the national top 50.

Where the national cleanest cohort concentrates

Among the unfiltered national top 50 (highest Good-day share, ≥100 monitored days), Virginia contributes 6 counties , followed by Wyoming (4). State filters rank every qualifying county inside one jurisdiction.

Compare any two counties

For a side-by-side annual change view, open the county compare tool.

Cleanest of the clean: lowest median AQI

Cleanest of the clean: lowest median AQI

Among the top counties (all near a 100% Good-day record), the lowest typical AQI. Shorter is cleaner.

  1. 1 Roane, Tennessee 29
  2. 2 Putnam, Tennessee 30
  3. 3 Montgomery, Tennessee 32
  4. 4 Maury, Tennessee 33
  5. 5 Lawrence, Tennessee 33
  6. 6 DeKalb, Tennessee 34
  7. 7 Dyer, Tennessee 34
  8. 8 Claiborne, Tennessee 35
  9. 9 Madison, Tennessee 36
  10. 10 McMinn, Tennessee 37
  11. 11 Wilson, Tennessee 38
  12. 12 Anderson, Tennessee 39

Median AQI · EPA Air Quality System

Ranked counties

# County State Good Days % Median AQI
1 Claiborne Tennessee 97.3% 35 Good
2 Sevier Tennessee 96.7% 40 Good
3 DeKalb Tennessee 96.6% 34 Good
4 Anderson Tennessee 94.3% 39 Good
5 Wilson Tennessee 93.4% 38 Good
6 Jefferson Tennessee 90.7% 41 Good
7 Putnam Tennessee 90.0% 30 Good
8 Williamson Tennessee 88.9% 40 Good
9 Roane Tennessee 88.6% 29 Good
10 Loudon Tennessee 85.5% 39 Good
11 Montgomery Tennessee 83.8% 32 Good
12 Maury Tennessee 83.5% 33 Good
13 Sullivan Tennessee 82.0% 40 Good
14 Lawrence Tennessee 81.5% 33 Good
15 McMinn Tennessee 78.2% 37 Good
16 Dyer Tennessee 76.9% 34 Good
17 Madison Tennessee 74.3% 36 Good
18 Blount Tennessee 71.5% 44 Good
19 Sumner Tennessee 69.3% 44 Good
20 Hamilton Tennessee 64.9% 44 Good
21 Knox Tennessee 63.0% 46 Good
22 Shelby Tennessee 60.3% 47 Good
23 Davidson Tennessee 52.9% 49 Good

Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS). Good Days % is the share of monitored days with AQI at or below 50. Counties ranked by good_pct descending

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Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.