Air Quality Rankings for Ohio 2026

Ohio has 40 cities with EPA air quality data. Harrison, Ohio has the cleanest air with a 5-year average AQI of 10. Cuyahoga, Ohio has the highest AQI at 56.

#	City	5yr Avg AQI	Current AQI	Worst Pollutant	Trend	Grade
1	Harrison, Ohio	10	33	CO	Worsening	B
2	Columbiana, Ohio	12	11	PM10	Improving	A
3	Belmont, Ohio	18	31	NO2	Worsening	B
4	Scioto, Ohio	21	44	PM10	Worsening	C
5	Athens, Ohio	30	31	PM2.5	Improving	B
6	Adams, Ohio	34	39	PM2.5	Stable	B
7	Fayette, Ohio	36	35	Ozone	Stable	B
8	Noble, Ohio	37	39	Ozone	Stable	B
9	Wood, Ohio	38	40	Ozone	Stable	B
10	Lorain, Ohio	39	37	PM2.5	Stable	B
11	Ashtabula, Ohio	39	42	Ozone	Stable	B
12	Delaware, Ohio	39	41	Ozone	Stable	B
13	Knox, Ohio	40	42	Ozone	Stable	B
14	Licking, Ohio	40	43	Ozone	Stable	B
15	Washington, Ohio	40	42	Ozone	Stable	B
16	Miami, Ohio	40	43	Ozone	Stable	B
17	Portage, Ohio	40	43	Ozone	Worsening	C
18	Greene, Ohio	41	44	PM2.5	Improving	B
19	Madison, Ohio	41	44	Ozone	Stable	B
20	Lake, Ohio	41	42	PM2.5	Improving	B
21	Clinton, Ohio	41	44	Ozone	Stable	B
22	Geauga, Ohio	41	41	Ozone	Stable	B
23	Medina, Ohio	42	44	PM2.5	Improving	B
24	Clermont, Ohio	42	41	PM2.5	Improving	B
25	Allen, Ohio	42	44	Ozone	Worsening	C
26	Trumbull, Ohio	44	48	PM2.5	Stable	C
27	Lawrence, Ohio	44	46	PM2.5	Improving	B
28	Lucas, Ohio	44	45	PM2.5	Improving	B
29	Warren, Ohio	45	44	PM2.5	Improving	B
30	Preble, Ohio	45	46	PM2.5	Stable	C
31	Summit, Ohio	46	46	PM2.5	Stable	C
32	Mahoning, Ohio	46	49	PM2.5	Stable	C
33	Clark, Ohio	49	50	PM2.5	Stable	C
34	Butler, Ohio	50	56	Ozone	Worsening	D
35	Franklin, Ohio	50	54	PM2.5	Stable	C
36	Jefferson, Ohio	50	49	PM2.5	Improving	B
37	Stark, Ohio	51	52	PM2.5	Worsening	C
38	Montgomery, Ohio	51	51	PM2.5	Stable	C
39	Hamilton, Ohio	55	54	PM2.5	Improving	C
40	Cuyahoga, Ohio	56	57	PM2.5	Worsening	C

Air quality data for Ohio is sourced from the EPA Air Quality System (AQS), which monitors outdoor air quality at thousands of stations nationwide.
— EPA Air Quality System

Frequently Asked Questions

Harrison, Ohio has the best air quality in Ohio with a 5-year average AQI of 10 and a grade of B.

Ohio has 40 cities with EPA air quality monitoring data in our database, covering multiple years of AQI measurements.

The Air Quality Index (AQI) measures five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Lower AQI values indicate cleaner air — 0-50 is "Good," while 150+ is "Unhealthy."

Sources: EPA Air Quality System (AQS)

Cities ranked by 5-year average AQI (lower is better). Grades factor in average AQI, trend direction, unhealthy days, and dominant pollutant.

Cleanest Cities Nationwide →All Air Quality in Ohio →