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.

Compiled by PlainAirData · August 23, 2026

100.0%
#1 Karnes, Texas: 44
Counties ranked

Karnes County, Texas leads the 2025 cleanest-air list among 44 ranked U.S. counties (100.0% Good)

According to the U.S. EPA Air Quality System, this ranking orders 44 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 44 for Good-day share at 100.0% (2 counties tied at 100% Good; median AQI breaks ties).
#1 median AQI: #1 median AQI: 6
Counties ranked: Counties ranked: 44
Tied at 100% Good: Tied at 100% Good: 2

Data updated August 2026 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. 2 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.

Showing 44 matching Texas 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

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

Median AQI · EPA Air Quality System

Ranked counties

#	County	State	Good Days %	Median AQI	Good Days	Days Monitored	Day driver
1	Karnes	Texas	100.0%	6 Good	356	356	-
2	Wilson	Texas	100.0%	8 Good	362	362	-
3	Rockwall	Texas	96.8%	31 Good	276	285	Ozone
4	Polk	Texas	94.8%	33 Good	326	344	Ozone
5	Potter	Texas	94.1%	16 Good	301	320	PM2.5
6	Lubbock	Texas	92.9%	24 Good	314	338	PM2.5
7	Hunt	Texas	91.7%	34 Good	332	362	Ozone
8	Smith	Texas	90.4%	35 Good	330	365	Ozone
9	Ellis	Texas	89.2%	35 Good	323	362	Ozone
10	Victoria	Texas	86.7%	34 Good	312	360	Ozone
11	Gregg	Texas	86.6%	36 Good	316	365	Ozone
12	Johnson	Texas	85.5%	37 Good	300	351	Ozone
13	Hood	Texas	83.4%	38 Good	296	355	Ozone
14	Randall	Texas	82.8%	41 Good	298	360	Ozone
15	Parker	Texas	81.8%	38 Good	283	346	Ozone
16	Brazoria	Texas	80.8%	35 Good	295	365	Ozone
17	Atascosa	Texas	76.0%	35 Good	259	341	PM2.5
18	Collin	Texas	75.8%	40 Good	272	359	Ozone
19	Brewster	Texas	74.7%	43 Good	272	364	Ozone
20	Ector	Texas	72.3%	39 Good	259	358	PM2.5
21	Brazos	Texas	68.5%	40 Good	233	340	PM2.5
22	Kaufman	Texas	66.0%	44 Good	241	365	PM2.5
23	Bell	Texas	66.0%	45 Good	241	365	Ozone
24	Harrison	Texas	64.4%	44 Good	235	365	PM2.5
25	Maverick	Texas	63.0%	42 Good	221	351	PM2.5
26	Orange	Texas	60.2%	45 Good	219	364	PM2.5
27	Galveston	Texas	59.7%	45 Good	218	365	Ozone
28	Navarro	Texas	59.2%	47 Good	215	363	Ozone
29	Denton	Texas	57.8%	47 Good	211	365	Ozone
30	Bowie	Texas	55.0%	48 Good	188	342	PM2.5
31	Kleberg	Texas	51.7%	49 Good	62	120	PM2.5
32	Webb	Texas	49.9%	51 Moderate	182	365	PM2.5
33	Jefferson	Texas	48.0%	51 Moderate	175	365	PM2.5
34	McLennan	Texas	46.6%	51 Moderate	170	365	PM2.5
35	Hidalgo	Texas	44.4%	52 Moderate	162	365	PM2.5
36	Travis	Texas	43.6%	53 Moderate	159	365	PM2.5
37	Bexar	Texas	43.3%	52 Moderate	158	365	PM2.5
38	Dallas	Texas	40.5%	53 Moderate	148	365	PM2.5
39	Nueces	Texas	40.5%	53 Moderate	148	365	PM2.5
40	Montgomery	Texas	39.1%	53 Moderate	142	363	PM2.5
41	Tarrant	Texas	31.8%	56 Moderate	116	365	PM2.5
42	Cameron	Texas	29.9%	57 Moderate	109	365	PM2.5
43	El Paso	Texas	18.1%	70 Moderate	66	365	PM10
44	Harris	Texas	11.0%	62 Moderate	40	365	PM2.5

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

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.