Which county in Oregon has the best air quality?

Based on 2022 EPA AQS data, Benton County had the best air quality in Oregon with a median AQI of 21 and 183 good-air days.

2024 monitoring year Public dataset EPA AQS

Oregon Air Quality Rankings

Compiled by PlainEnviro Editorial, Environmental Data Editorial Team · July 13, 2026

County-level AQI rollup using EPA Air Quality System monitor records. Refreshed as new EPA AQS data lands.

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County-by-county air quality data for Oregon based on EPA AQS annual AQI readings. Data covers 23 monitored counties for 2022.

Oregon (2022): 23 counties monitored. State average median AQI: 33 (national average: 38.8). 76% of monitored days rated "Good." Most unhealthy air: Harney County (20 days above AQI 100).

Oregon air quality on this page is drawn from the EPA Air Quality System (AQS), which aggregates daily readings from federal, state, tribal, and local monitors into annual summaries per county. The current dataset covers 23 Oregon counties with at least ten days of valid AQI readings in 2022, out of the state's total monitored counties.

The state-average median AQI across those counties is 33, compared with a national average of 38.8 in the same reporting period. On average, 76% of monitored days fell into the "Good" AQI bucket (0–50). The heaviest burden of unhealthy days lands on Harney County (20 days above AQI 100), while Benton County records the cleanest air with a median AQI of 21.

AQI values translate ambient concentrations of pollutants (ozone, PM2.5, PM10, NO₂, SO₂, CO) onto a single 0–500 scale with six health-based bands. A low median AQI reflects typical daily conditions; peak values matter separately because short-term exposure drives most acute health effects. Counties without monitors are not "clean" - they are simply unmeasured by EPA AQS. For site-specific exposure guidance, check AirNow.gov alongside the county detail links below.

Counties with Data

State Avg Median AQI

National Avg Median AQI

38.8

Avg Good Days %

76%

Which Oregon counties have the worst air quality?

Ranked by median AQI (higher = worse). Click a county for full environmental data.

#	County	Median AQI	Good Days	Good %	Unhealthy Days	Peak AQI
1	Douglas	53	21	46%	0	69
2	Grant	49	189	52%	14	204
3	Harney	46	200	55%	20	271
4	Lane	44	219	60%	6	216
5	Jackson	41	262	72%	1	155
6	Deschutes	39	258	70%	7	176
7	Umatilla	38	272	74%	0	117
8	Marion	35	298	81%	0	129
9	Multnomah	35	311	85%	0	93
10	Washington	33	309	84%	0	105
11	Klamath	33	259	71%	7	207
12	Clackamas	30	325	89%	0	127
13	Josephine	29	284	78%	0	146
14	Lake	28	286	78%	2	153
15	Baker	28	279	76%	2	155
16	Columbia	26	354	97%	0	74
17	Jefferson	26	289	79%	0	142
18	Linn	25	320	87%	0	86
19	Crook	24	282	77%	3	173
20	Wasco	23	317	87%	0	93
21	Union	23	303	83%	0	128
22	Wallowa	23	283	80%	0	125
23	Benton	21	183	89%	0	68

Frequently Asked Questions

What is the air quality like in Oregon?

In 2022, Oregon had an average median AQI of 33 across 23 monitored counties, with 76% of monitored days rated "Good" (AQI 0–50). The national average median AQI is 38.8.

Which county in Oregon has the worst air quality?

Based on 2022 EPA AQS data, Harney County had the most unhealthy air days in Oregon - 20 days above AQI 100, with a median AQI of 46.

Explore More

National AQI Rankings → Oregon Full Profile → Oregon Water Quality →

About This Data

Air quality data is from the EPA Air Quality System (AQS), Annual AQI by County dataset. Counties with fewer than 10 monitored days are excluded. "Unhealthy days" counts days with AQI above 100 (Unhealthy for Sensitive Groups or worse). All data is for 2022.

Source: U.S. Environmental Protection Agency, Air Quality System (AQS) U.S. Environmental Protection Agency, Air Quality System (AQS)

Read our methodology - how this data is sourced, computed, and verified.

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Data sourced from the U.S. Environmental Protection Agency (EPA). See our methodology for details. Retrieved and formatted by PlainEnviro Editorial