Vernon County, Wisconsin air quality history

Daily Air Quality Index summaries from EPA monitors in Vernon, Wisconsin, 1983–2010.

90%

Good days in 2010

Median daily AQI, 2010

Days above 100 in 2010

216

Days with an AQI in 2010 (of 365)

In 2010, EPA reported a daily Air Quality Index (AQI) for Vernon, Wisconsin on 216 days. 194 of those days (90%) were in the Good range, and the median daily AQI was 39. That median is about the same as the typical monitored county in Wisconsin (median 40 across 31 counties), and lower than the typical monitored U.S. county (44). The main pollutant was ozone on 216 days. Across the years with fuller monitoring, the share of Good days fell: an average of 94% in 1983–1990 versus 90% in 2008–2010.

EPA did not report an AQI for every day of 2010 here (216 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

The most recent year with data for this county is 2010; EPA's files for 2011–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1989) 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, 2010

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
Ozone	216	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Unhealthy	Median AQI	90th pct.	Max AQI	Main pollutant
2010	216	194	22	0	0	39	51	93	Ozone
2009	210	191	19	0	0	36	50	84	Ozone
2008	210	189	20	1	0	40	51	101	Ozone
2007	195	154	35	6	0	42	64	136	Ozone
2006	183	144	38	1	0	43	61	108	Ozone
2005	203	153	45	4	1	44	80	166	Ozone
2004	191	169	22	0	0	37	54	84	Ozone
2003	180	110	64	6	0	46	90	119	Ozone
2002	183	136	41	6	0	43	80	112	Ozone
2001	184	146	34	4	0	41	71	108	Ozone
2000	181	153	23	5	0	40	61	133	Ozone
1999	194	150	35	8	1	40	80	174	Ozone
1998	210	162	42	6	0	42	67	150	Ozone
1997	202	159	39	4	0	39	71	140	Ozone
1996	206	184	21	1	0	36	51	129	Ozone
1995	211	176	31	4	0	36	71	129	Ozone
1994	217	198	18	1	0	35	50	115	Ozone
1993	239	227	12	0	0	33	45	100	Ozone
1992	285	256	25	4	0	31	54	136	Ozone
1991	288	244	35	9	0	38	64	147	Ozone
1990	272	223	45	4	0	39	61	105	Ozone
1989	30	30	0	0	0	19	31	47	PM10
1984	358	358	0	0	0	9	20	42	NO2
1983	354	353	1	0	0	8	20	51	NO2

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 Wisconsin with a similar median AQI in 2010

All monitored counties in Wisconsin

Source: U.S. EPA AirData, “Annual AQI by County” files for 1983–2010 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem