EnviroNearby

Oneida County, Wisconsin air quality history

Daily Air Quality Index summaries from EPA monitors in Oneida, Wisconsin, 1989–2011.

90%
Good days in 2011
38
Median daily AQI, 2011
0
Days above 100 in 2011
197
Days with an AQI in 2011 (of 365)

In 2011, EPA reported a daily Air Quality Index (AQI) for Oneida, Wisconsin on 197 days. 178 of those days (90%) were in the Good range, and the median daily AQI was 38. That median is about the same as the typical monitored county in Wisconsin (median 40 across 28 counties), and lower than the typical monitored U.S. county (44). The main pollutant was ozone on 197 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 92% in 1989–1995 versus 91% in 2009–2011.

EPA did not report an AQI for every day of 2011 here (197 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 2011; EPA's files for 2012–2025 contain no row for it, which usually means its monitors stopped reporting.

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.

Share of monitored days in each AQI category, by year0%25%50%75%100%1989: Good 175 of 207 days1989: Moderate 30 of 207 days1989: Unhealthy for Sensitive Groups 2 of 207 days19891994: Good 120 of 122 days1994: Moderate 2 of 122 days1995: Good 160 of 174 days1995: Moderate 13 of 174 days1995: Unhealthy for Sensitive Groups 1 of 174 days19951996: Good 171 of 184 days1996: Moderate 11 of 184 days1996: Unhealthy for Sensitive Groups 2 of 184 days1997: Good 162 of 181 days1997: Moderate 18 of 181 days1997: Unhealthy for Sensitive Groups 1 of 181 days19971998: Good 147 of 180 days1998: Moderate 30 of 180 days1998: Unhealthy for Sensitive Groups 2 of 180 days1998: Unhealthy 1 of 180 days1999: Good 148 of 180 days1999: Moderate 22 of 180 days1999: Unhealthy for Sensitive Groups 8 of 180 days1999: Unhealthy 2 of 180 days19992000: Good 141 of 162 days2000: Moderate 19 of 162 days2000: Unhealthy for Sensitive Groups 2 of 162 days2001: Good 142 of 180 days2001: Moderate 32 of 180 days2001: Unhealthy for Sensitive Groups 6 of 180 days20012002: Good 155 of 182 days2002: Moderate 26 of 182 days2002: Unhealthy for Sensitive Groups 1 of 182 days2003: Good 136 of 181 days2003: Moderate 41 of 181 days2003: Unhealthy for Sensitive Groups 4 of 181 days20032004: Good 168 of 187 days2004: Moderate 18 of 187 days2004: Unhealthy for Sensitive Groups 1 of 187 days2005: Good 140 of 184 days2005: Moderate 40 of 184 days2005: Unhealthy for Sensitive Groups 4 of 184 days20052006: Good 158 of 184 days2006: Moderate 26 of 184 days2007: Good 176 of 198 days2007: Moderate 18 of 198 days2007: Unhealthy for Sensitive Groups 4 of 198 days20072008: Good 171 of 196 days2008: Moderate 24 of 196 days2008: Unhealthy for Sensitive Groups 1 of 196 days2009: Good 183 of 198 days2009: Moderate 15 of 198 days20092010: Good 180 of 199 days2010: Moderate 19 of 199 days2011: Good 178 of 197 days2011: Moderate 19 of 197 days2011
  • 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 and 90th-percentile daily AQI, by year0501001989: 90th percentile AQI 611994: 90th percentile AQI 441995: 90th percentile AQI 491996: 90th percentile AQI 501997: 90th percentile AQI 511998: 90th percentile AQI 741999: 90th percentile AQI 772000: 90th percentile AQI 512001: 90th percentile AQI 672002: 90th percentile AQI 582003: 90th percentile AQI 712004: 90th percentile AQI 512005: 90th percentile AQI 742006: 90th percentile AQI 542007: 90th percentile AQI 542008: 90th percentile AQI 542009: 90th percentile AQI 502010: 90th percentile AQI 502011: 90th percentile AQI 501989: Median AQI 381994: Median AQI 311995: Median AQI 351996: Median AQI 371997: Median AQI 361998: Median AQI 391999: Median AQI 392000: Median AQI 362001: Median AQI 402002: Median AQI 372003: Median AQI 422004: Median AQI 382005: Median AQI 412006: Median AQI 382007: Median AQI 372008: Median AQI 392009: Median AQI 362010: Median AQI 362011: Median AQI 381989199519971999200120032005200720092011
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2011

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.

PollutantDays as main pollutantShare of monitored days
Ozone197100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20111971781900003850100Ozone
2010199180190000365093Ozone
2009198183150000365090Ozone
20081961712410003954108Ozone
20071981761840003754136Ozone
2006184158260000385487Ozone
20051841404040004174133Ozone
20041871681810003851108Ozone
20031811364140004271112Ozone
20021821552610003758105Ozone
20011801423260004067122Ozone
20001621411920003651115Ozone
19991801482282003977161Ozone
19981801473021003974151Ozone
19971811621810003651108Ozone
19961841711120003750126Ozone
19951741601310003549108Ozone
199412212020000314464Ozone
19892071753020003861112Ozone

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 Wisconsin

Source: U.S. EPA AirData, “Annual AQI by County” files for 1989–2011 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem