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/

How many days a year the air is unhealthy to breathe, blended with fine particle pollution.

By The Honest Local · 49 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. 2Texas89.11 days Unhealthy or worse
No. 3Minnesota86.41 days Unhealthy or worse
No. 4Illinois82.51 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 49

The full ranking worst score, 0 to 100

	Place	Bad Air Scoreout of 100	Unhealthy days pct	PM2.5µg/m³
1	California	89.8	498	982
2	Texas	89.1	191	987
3	Minnesota	86.4	192	981
4	Illinois	82.5	188	977
5	North Dakota	80.2	295	866
6	Kansas	79.9	081	979
7	Michigan	77.2	183	872
8	Arizona	75.9	193	859
9	Wisconsin	75.6	188	864
10	Indiana	74.9	070	980
11	Ohio	73.7	065	983
12	Oklahoma	67.7	068	867
13	Missouri	62.1	071	853
14	South Carolina	62.1	064	860
15	Iowa	60.4	069	852
16	Kentucky	57.4	067	748
17	Arkansas	53.6	013	1095
18	New York	53.4	065	742
19	Delaware	50.5	070	731
20	New Mexico	49.4	182	617
21	New Jersey	49.2	066	733
22	Alaska	43.8	082	56
23	Connecticut	43.5	072	615
24	Maine	41.8	066	617
25	Georgia	40.7	011	871
26	Utah	39.6	063	616
27	Rhode Island	38.9	068	610
28	Washington	37.9	062	614
29	Mississippi	35.8	07	865
30	Louisiana	35.4	09	862
31	Vermont	33.6	063	55
32	Alabama	33.4	013	854
33	Wyoming	30.6	061	30
34	Pennsylvania	27.5	03	852
35	North Carolina	26.8	03	850
36	Tennessee	24.8	01	748
37	Florida	23.8	011	736
38	West Virginia	20.2	00	740
39	South Dakota	17.9	02	734
40	Nebraska	15.9	05	727
41	Virginia	14.3	01	728
42	Maryland	12.9	08	618
43	Colorado	9.9	012	68
44	Massachusetts	8.9	07	611
45	Idaho	8.9	09	69
46	Nevada	8.3	05	612
47	Montana	6.3	06	57
48	Hawaii	5.3	010	41
49	New Hampshire	3.3	04	53

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.