Wallowa County, Oregon air quality history

Daily Air Quality Index summaries from EPA monitors in Wallowa, Oregon, 2000–2025.

85%

Good days in 2025

Median daily AQI, 2025

Days above 100 in 2025

365

Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Wallowa, Oregon on 365 days. 311 of those days (85%) were in the Good range, and the median daily AQI was 26. That median is lower than the typical monitored county in Oregon (median 29 across 21 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 365 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 84% in 2004–2006 versus 84% in 2023–2025.

Years with fewer than 120 monitored days (2000, 2001, 2002, 2003) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median daily AQI
90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

Pollutant	Days as main pollutant	Share of monitored days
Fine particles (PM2.5)	365	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Unhealthy	Very Unhealthy	Median AQI	90th pct.	Max AQI	Main pollutant
2025	365	311	54	0	0	0	26	53	88	PM2.5
2024	355	283	71	1	0	0	23	61	125	PM2.5
2023	365	315	50	0	0	0	25	53	82	PM2.5
2022	343	270	65	3	5	0	27	58	195	PM2.5
2021	365	280	75	6	4	0	26	63	162	PM2.5
2020	366	288	71	0	6	1	27	58	222	PM2.5
2019	363	289	73	1	0	0	29	56	103	PM2.5
2018	329	251	76	2	0	0	28	60	118	PM2.5
2017	353	271	73	6	3	0	27	64	177	PM2.5
2016	357	308	49	0	0	0	23	55	78	PM2.5
2015	364	289	66	4	5	0	26	58	185	PM2.5
2014	365	302	60	3	0	0	23	57	121	PM2.5
2013	364	260	104	0	0	0	37	58	98	PM2.5
2012	358	298	58	2	0	0	26	56	150	PM2.5
2011	362	306	56	0	0	0	23	55	88	PM2.5
2010	362	293	68	0	1	0	26	53	162	PM2.5
2009	363	286	77	0	0	0	31	57	77	PM2.5
2008	363	285	78	0	0	0	29	56	83	PM2.5
2007	364	275	84	5	0	0	28	59	136	PM2.5
2006	362	282	79	1	0	0	29	58	127	PM2.5
2005	364	289	75	0	0	0	25	59	99	PM2.5
2004	121	115	6	0	0	0	16	39	61	PM2.5
2003	100	98	2	0	0	0	14	34	56	PM2.5
2002	112	110	2	0	0	0	18	35	60	PM2.5
2001	110	107	3	0	0	0	17	37	61	PM2.5
2000	34	33	1	0	0	0	18	34	54	PM2.5

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Oregon with a similar median AQI in 2025

All monitored counties in Oregon

Source: U.S. EPA AirData, “Annual AQI by County” files for 2000–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem