Douglas County, Oregon air quality history

Daily Air Quality Index summaries from EPA monitors in Douglas, Oregon, 1990–2022.

83%

Good days in 2021

Median daily AQI, 2021

Days above 100 in 2021

365

Days with an AQI in 2021 (of 365)

In 2021, EPA reported a daily Air Quality Index (AQI) for Douglas, Oregon on 365 days. 304 of those days (83%) were in the Good range, and the median daily AQI was 29. That median is about the same as the typical monitored county in Oregon (median 31 across 23 counties), and lower than the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 365 days. Across the years with fuller monitoring, the share of Good days fell: an average of 90% in 1992–1994 versus 78% in 2019–2021.

The most recent year with data for this county is 2022; EPA's files for 2023–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1990, 1991, 1995, 2022) 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, 2021

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	Hazardous	Median AQI	90th pct.	Max AQI	Main pollutant
2022	46	21	25	0	0	0	0	53	62	69	PM2.5
2021	365	304	56	3	2	0	0	29	54	186	PM2.5
2020	366	278	78	1	1	2	6	29	62	902	PM2.5
2019	347	256	91	0	0	0	0	32	64	82	PM2.5
2018	336	256	78	2	0	0	0	29	61	135	PM2.5
2017	359	266	86	4	3	0	0	29	62	172	PM2.5
2016	339	306	33	0	0	0	0	23	50	69	PM2.5
2015	365	292	72	1	0	0	0	26	56	141	PM2.5
2014	364	301	63	0	0	0	0	27	56	78	PM2.5
2013	365	260	105	0	0	0	0	41	64	93	PM2.5
2012	362	306	56	0	0	0	0	26	53	73	PM2.5
2011	360	286	74	0	0	0	0	27	58	95	PM2.5
2010	363	316	47	0	0	0	0	28	52	68	PM2.5
2009	360	264	94	2	0	0	0	37	58	107	PM2.5
2008	362	256	106	0	0	0	0	36	62	93	PM2.5
2007	360	270	90	0	0	0	0	32	61	92	PM2.5
2006	360	241	118	1	0	0	0	39	66	107	PM2.5
2005	128	64	64	0	0	0	0	52	72	90	PM2.5
1995	76	76	0	0	0	0	0	15	29	38	PM10
1994	150	139	11	0	0	0	0	21	44	70	PM10
1993	164	146	18	0	0	0	0	22	51	67	PM10
1992	151	133	18	0	0	0	0	26	52	66	PM10
1991	114	96	18	0	0	0	0	30	55	94	PM10
1990	4	2	1	1	0	0	0	52	102	102	PM10

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.

All monitored counties in Oregon

Source: U.S. EPA AirData, “Annual AQI by County” files for 1990–2022 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem