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.

100.0%
#1 Karnes, Texas
50
Counties ranked

Karnes County, Texas leads the 2025 cleanest-air list among 50 ranked U.S. counties (100.0% Good)

According to the U.S. EPA Air Quality System, this ranking orders 50 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
Karnes County, Texas ranks #1 of 50 for Good-day share at 100.0% (7 counties tied at 100% Good; median AQI breaks ties).
#1 median AQI
#1 median AQI: 6
Counties ranked
Counties ranked: 50
Tied at 100% Good
Tied at 100% Good: 7

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. 7 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

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

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 Karnes, Texas 6
  2. 2 Wilson, Texas 8
  3. 3 Carbon, Wyoming 8
  4. 4 Kenai Peninsula, Alaska 9
  5. 5 Sonoma, California 9
  6. 6 Uinta, Wyoming 9
  7. 7 Mayagnez, Puerto Rico 9
  8. 8 Lincoln, Wyoming 10
  9. 9 Gallatin, Montana 11
  10. 10 Navajo, Arizona 13
  11. 11 Park, Wyoming 13
  12. 12 Pacific, Washington 16

Median AQI · EPA Air Quality System

Ranked counties

# County State Good Days % Median AQI
1 Karnes Texas 100.0% 6 Good
2 Wilson Texas 100.0% 8 Good
3 Carbon Wyoming 100.0% 8 Good
4 Kenai Peninsula Alaska 100.0% 9 Good
5 Sonoma California 100.0% 9 Good
6 Uinta Wyoming 100.0% 9 Good
7 Martin North Carolina 100.0% 31 Good
8 Pacific Washington 99.7% 16 Good
9 Denali Alaska 99.7% 33 Good
10 Navajo Arizona 99.5% 13 Good
11 Lake California 99.2% 31 Good
12 Solano California 99.2% 33 Good
13 Lincoln Wyoming 98.9% 10 Good
14 Taos New Mexico 98.9% 16 Good
15 Liberty Florida 98.5% 33 Good
16 Gallatin Montana 98.1% 11 Good
17 Flagler Florida 98.1% 34 Good
18 Maui Hawaii 98.1% 21 Good
19 Park Wyoming 98.0% 13 Good
20 Elmore Alabama 97.9% 34 Good
21 Prince Edward Virginia 97.8% 33 Good
22 Mayagnez Puerto Rico 97.8% 9 Good
23 Knox Maine 97.8% 33 Good
24 Fauquier Virginia 97.5% 34 Good
25 Lenoir North Carolina 97.5% 35 Good
26 Skagit Washington 97.5% 25 Good
27 Meade South Dakota 97.4% 36 Good
28 Jefferson Washington 97.3% 20 Good
29 Grays Harbor Washington 97.3% 22 Good
30 Honolulu Hawaii 97.3% 29 Good
31 Oswego New York 97.3% 34 Good
32 Claiborne Tennessee 97.3% 35 Good
33 Hamilton New York 97.2% 34 Good
34 Caldwell North Carolina 97.1% 36 Good
35 Teton Montana 97.1% 12 Good
36 Greenup Kentucky 96.9% 36 Good
37 Rockwall Texas 96.8% 31 Good
38 Suffolk City Virginia 96.7% 38 Good
39 York Maine 96.7% 34 Good
40 Caroline Virginia 96.7% 35 Good
41 Merrimack New Hampshire 96.7% 37 Good
42 Clark Arkansas 96.7% 34 Good
43 Sevier Tennessee 96.7% 40 Good
44 Hanover Virginia 96.7% 36 Good
45 DeKalb Tennessee 96.6% 34 Good
46 Yalobusha Mississippi 96.6% 34 Good
47 Blaine Idaho 96.6% 17 Good
48 Macon North Carolina 96.5% 32 Good
49 St. Lucie Florida 96.4% 34 Good
50 Stafford Virginia 96.4% 35 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 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.