States with the Worst Air, California Leads (2026)

Name: Worst air quality by city and state, The Honest Local
Creator: The Honest Local
License: https://creativecommons.org/licenses/by/4.0/

California has the worst air of the 50 states we rank, with a Bad Air Score of 89.8 out of 100 and 4% of days rated Unhealthy or worse (EPA, 2025). Texas is next, with a Bad Air Score of 89.3.

By The Honest Local · 50 states · every value links to its public source

89.8California leads on The Honest Local Bad Air Score, all 50 statesHow many days a year the air is unhealthy to breathe, blended with fine particle pollution.

The top five states Bad Air Score out of 100, and the readings behind it

No. 1California89.84 days Unhealthy or worse
No. 2Texas89.31 days Unhealthy or worse
No. 3Minnesota86.41 days Unhealthy or worse
No. 4Illinois82.91 days Unhealthy or worse
No. 5North Dakota80.22 days Unhealthy or worse

States with the Worst Air on the map

Bad Air Score, states hover for the numbers, click for every one

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The share of monitored days the EPA rated Unhealthy or worse, blended with the average fine particle pollution in the air over the year.

States with the Worst Air, all 50

The full ranking worst score, 0 to 100

	Place	Bad Air Scoreout of 100	Unhealthy days pct	PM2.5µg/m³
1	California	89.8	3.798	8.882
2	Texas	89.3	1.191	987
3	Minnesota	86.4	1.292	8.781
4	Illinois	82.9	0.889	8.677
5	North Dakota	80.2	1.595	866
6	Kansas	80.1	0.481	8.779
7	Michigan	78	0.585	8.372
8	Arizona	76.2	1.493	7.859
9	Wisconsin	75.6	0.688	864
10	Indiana	74.6	0.269	8.780
11	Ohio	73.3	0.164	8.883
12	Oklahoma	68	0.269	8.167
13	Missouri	64.4	0.376	7.653
14	Arkansas	62.3	030	9.595
15	South Carolina	62.1	0.164	7.960
16	Iowa	60.4	0.269	7.652
17	Kentucky	55.8	0.164	7.548
18	New York	53.1	0.164	7.242
19	New Mexico	50.9	0.585	6.117
20	Georgia	50.4	030	8.371
21	Delaware	50.1	0.269	6.731
22	New Jersey	48.5	0.164	6.833
23	Mississippi	47.4	030	865
24	Louisiana	46.1	030	862
25	Connecticut	45.8	0.376	616
26	Alaska	43.7	0.481	5.36
27	Alabama	41.5	030	7.653
27	Pennsylvania	41.5	030	7.653
29	Maine	40.8	0.164	6.118
30	Utah	40.2	0.164	6.117
31	North Carolina	40.1	030	7.550
32	Oregon	39.5	0.164	5.915
32	Rhode Island	39.5	0.269	5.710
34	Tennessee	39.1	030	7.548
35	Washington	38.9	0.164	5.814
36	West Virginia	35.5	030	7.141
37	Vermont	34.2	0.164	5.25
38	Florida	33.5	030	6.937
39	South Dakota	32.2	030	6.834
40	Wyoming	31.9	0.164	3.10
41	Virginia	29.2	030	6.729
42	Nebraska	28.6	030	6.627
43	Maryland	24.2	030	6.119
44	Nevada	20.9	030	5.812
45	Massachusetts	20.3	030	5.711
46	Idaho	19.4	030	5.69
47	Colorado	18.9	030	5.68
48	Montana	18.3	030	5.47
49	New Hampshire	16.3	030	4.93
50	Hawaii	15.3	030	41

Sources and method

EPA annual air quality by county, 2025 · 2025, with 2024 where 2025 is not yet filed
EPA annual air quality by county, 2024
EPA annual fine particle readings by monitor, 2025

How we got this. The Bad Air Score is The Honest Local’s own recipe. Each source ranks every place on its own from 0 to 100 and the score is the average, so a place has to do well on all of them to lead. The same two EPA sources and the same state method as our clean air list, read from the other end. The share of monitored days in the year rated Unhealthy or worse, leaving out the milder Unhealthy for Sensitive Groups tier, blended with the average fine particle concentration the EPA's monitors measured. Each source ranks every place on its own and the average of the two ranks is the score that decides the list. The plain share of unhealthy days is still what we show you. A city uses its own county. For a state we never hand you one county's reading and call it the state's. We weight every county in the state by population, for each source on its own. Connecticut uses a plain average of its covered counties, for the reason given on the clean air list. It refreshes once a year, when the EPA publishes the prior year. For California, that means population-weighted mean of % across 52 EPA-covered counties in California (of the state's total counties; many rural counties have no monitor).

Rankings by The Honest Local from public data, one page per list, refreshed on each source’s own cycle. Places with no reading are left out rather than estimated. Every value on this page carries its source in the page’s structured data.

Photos Shutterstock/UladzikKryhin · Shutterstock/F · Shutterstock.