Olmsted County, Minnesota air quality history

Daily Air Quality Index summaries from EPA monitors in Olmsted, Minnesota, 1980–2025.

69%

Good days in 2025

Median daily AQI, 2025

Days above 100 in 2025

344

Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Olmsted, Minnesota on 344 days. 239 of those days (69%) were in the Good range, and the median daily AQI was 39. That median is about the same as the typical monitored county in Minnesota (median 37 across 21 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 230 days. Across the years with fuller monitoring, the share of Good days rose: an average of 48% in 1980–1982 versus 62% in 2023–2025.

Years with fewer than 120 monitored days (1997, 1998, 1999, 2000, 2001, 2002…) 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)	230	67%
Ozone	114	33%

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	344	239	97	5	3	0	39	65	166	PM2.5
2024	366	234	131	0	1	0	44	61	155	PM2.5
2023	365	189	161	14	1	0	49	76	167	PM2.5
2022	359	280	78	1	0	0	41	58	110	PM2.5
2021	361	275	84	2	0	0	39	61	125	Ozone
2020	366	292	73	1	0	0	38	56	111	Ozone
2019	364	271	93	0	0	0	40	60	86	PM2.5
2018	361	222	139	0	0	0	44	61	98	PM2.5
2017	365	254	111	0	0	0	42	59	87	PM2.5
2016	365	294	70	1	0	0	37	54	104	PM2.5
2015	365	274	90	1	0	0	41	58	116	PM2.5
2014	361	267	93	1	0	0	41	61	103	PM2.5
2013	365	232	133	0	0	0	44	63	100	PM2.5
2012	359	215	141	3	0	0	44	70	112	PM2.5
2011	360	203	157	0	0	0	46	70	99	PM2.5
2010	360	184	172	4	0	0	50	74	123	PM2.5
2009	365	192	169	4	0	0	49	71	127	PM2.5
2008	365	157	199	8	1	0	53	77	156	PM2.5
2007	354	144	202	6	2	0	55	78	153	PM2.5
2006	363	220	138	5	0	0	46	67	124	PM2.5
2005	359	170	178	9	2	0	52	77	153	PM2.5
2004	358	187	166	3	2	0	49	74	155	PM2.5
2003	310	115	185	10	0	0	54	80	136	PM2.5
2002	106	44	62	0	0	0	54	73	97	PM2.5
2001	109	47	61	1	0	0	52	76	102	PM2.5
2000	91	44	45	2	0	0	51	83	104	PM2.5
1999	28	28	0	0	0	0	16	34	37	PM10
1998	59	58	1	0	0	0	19	29	54	PM10
1997	58	58	0	0	0	0	19	29	36	PM10
1996	58	57	1	0	0	0	16	31	53	PM10
1995	278	278	0	0	0	0	23	33	46	CO
1994	359	356	3	0	0	0	26	39	59	CO
1993	362	354	8	0	0	0	31	42	60	CO
1992	324	310	14	0	0	0	30	43	58	CO
1991	361	337	24	0	0	0	34	48	72	CO
1990	352	320	32	0	0	0	31	49	74	CO
1989	361	321	40	0	0	0	35	52	77	CO
1988	327	279	47	1	0	0	32	54	131	CO
1987	326	293	32	1	0	0	26	51	136	CO
1986	362	325	37	0	0	0	33	51	91	CO
1985	362	280	80	0	0	2	40	60	214	CO
1984	364	254	110	0	0	0	43	66	90	CO
1983	361	234	124	3	0	0	44	70	115	CO
1982	362	206	155	1	0	0	48	70	101	CO
1981	364	187	169	7	1	0	50	77	159	CO
1980	366	128	216	18	3	1	58	91	204	CO

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 Minnesota with a similar median AQI in 2025

All monitored counties in Minnesota

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem