Multiple Sources · 53 states

States With Worst Air Quality

States with the worst air quality face serious public health challenges. California consistently ranks among the most polluted, particularly in the Central Valley and Los Angeles Basin where geographic features trap pollutants. Other states with poor air quality include those with heavy industrial activity, coal-fired power plants, or seasonal wildfire smoke. Climate change is making things worse: longer fire seasons send smoke across state lines, and hotter temperatures accelerate smog formation. Poor air quality disproportionately affects low-income communities near highways and factories.

Key Findings

1California leads with a air quality score of 56, followed by Illinois (56) and Arizona (58).
2Virgin Islands ranks last at 85, while California leads at 56.
3The national median across all states is 65 (Missouri at the midpoint).
4The top 10 states are: California, Illinois, Arizona, Mississippi, Colorado, Kansas, North Dakota, Oklahoma, Texas, Utah.

Full Ranking: States With Worst Air Quality

Source: Census ACS 2023 5-Year Estimates

#	State	AQ Score
1	Wyoming	66
2	Wisconsin	61
3	West Virginia	69
4	Washington	67
5	Virginia	71
6	Virgin Islands	85
7	Vermont	70
8	Utah	61
9	Texas	61
10	Tennessee	67
11	South Dakota	65
12	South Carolina	67
13	Rhode Island	67
14	Puerto Rico	76
15	Pennsylvania	67
16	Oregon	64
17	Oklahoma	61
18	Ohio	66
19	North Dakota	61
20	North Carolina	68
21	New York	67
22	New Mexico	66
23	New Jersey	64
24	New Hampshire	69
25	Nevada	64
26	Nebraska	72
27	Montana	67
28	Missouri	65
29	Mississippi	59
30	Minnesota	64
31	Michigan	66
32	Massachusetts	65
33	Maryland	69
34	Maine	70
35	Louisiana	65
36	Kentucky	65
37	Kansas	61
38	Iowa	65
39	Indiana	69
40	Illinois	56
41	Idaho	63
42	Hawaii	82
43	Georgia	65
44	Florida	64
45	District of Columbia	63
46	Delaware	65
47	Connecticut	65
48	Colorado	61
49	California	56
50	Arkansas	64
51	Arizona	58
52	Alaska	77
53	Alabama	67

Methodology

Rankings are based on American Community Survey (ACS) 2023 5-Year estimates from the US Census Bureau. All 50 states and the District of Columbia are included. The ACS surveys approximately 3.5 million households annually and provides detailed demographic, social, economic, and housing data. 5-Year estimates offer the most reliable data for state-level comparisons by averaging responses over a 60-month period. Percentages may not sum to 100% due to rounding.

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Frequently Asked Questions

California has the highest air quality score at 56, according to Census ACS 2023 data. Illinois and Arizona round out the top three.

Virgin Islands has the lowest air quality score at 85. Hawaii is second-lowest at 82.

The median across all 53 states is 65. Note that the national median and the state-level median are calculated differently — the state median represents the midpoint when all states are ranked.

This data comes from the American Community Survey (ACS) 2023 5-Year estimates published by the US Census Bureau. The ACS surveys approximately 3.5 million households annually and provides the most comprehensive demographic data available between decennial censuses.

Rankings are based on the latest available Census ACS data (currently 2023 5-Year estimates). The Census Bureau releases new ACS data annually, typically in September. Our data was last updated on April 12, 2026.

Sources: US Census Bureau ACS 2023 5-Year Estimates