EnviroNearby

Vilas County, Wisconsin air quality history

Daily Air Quality Index summaries from EPA monitors in Vilas, Wisconsin, 1981–2025.

92%
Good days in 2025
36
Median daily AQI, 2025
1
Days above 100 in 2025
199
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Vilas, Wisconsin on 199 days. 183 of those days (92%) were in the Good range, and the median daily AQI was 36. That median is about the same as the typical monitored county in Wisconsin (median 38 across 29 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 199 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 89% in 1981–1993 versus 87% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (199 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.

Years with fewer than 120 monitored days (1992) 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.

Share of monitored days in each AQI category, by year0%25%50%75%100%1981: Good 147 of 167 days1981: Moderate 18 of 167 days1981: Unhealthy for Sensitive Groups 2 of 167 days19811982: Good 132 of 156 days1982: Moderate 21 of 156 days1982: Unhealthy for Sensitive Groups 3 of 156 days1992: Good 58 of 58 days1993: Good 344 of 364 days1993: Moderate 16 of 364 days1993: Unhealthy for Sensitive Groups 4 of 364 days1994: Good 350 of 361 days1994: Moderate 11 of 361 days1995: Good 335 of 365 days1995: Moderate 28 of 365 days1995: Unhealthy for Sensitive Groups 2 of 365 days19951996: Good 339 of 361 days1996: Moderate 20 of 361 days1996: Unhealthy for Sensitive Groups 2 of 361 days1997: Good 339 of 359 days1997: Moderate 19 of 359 days1997: Unhealthy for Sensitive Groups 1 of 359 days1998: Good 332 of 365 days1998: Moderate 30 of 365 days1998: Unhealthy for Sensitive Groups 3 of 365 days1999: Good 250 of 298 days1999: Moderate 40 of 298 days1999: Unhealthy for Sensitive Groups 7 of 298 days1999: Unhealthy 1 of 298 days2000: Good 184 of 210 days2000: Moderate 24 of 210 days2000: Unhealthy for Sensitive Groups 2 of 210 days20002001: Good 178 of 214 days2001: Moderate 33 of 214 days2001: Unhealthy for Sensitive Groups 3 of 214 days2002: Good 241 of 276 days2002: Moderate 35 of 276 days2003: Good 240 of 299 days2003: Moderate 55 of 299 days2003: Unhealthy for Sensitive Groups 4 of 299 days2004: Good 209 of 241 days2004: Moderate 31 of 241 days2004: Unhealthy for Sensitive Groups 1 of 241 days2005: Good 156 of 210 days2005: Moderate 49 of 210 days2005: Unhealthy for Sensitive Groups 5 of 210 days20052006: Good 170 of 211 days2006: Moderate 41 of 211 days2007: Good 171 of 220 days2007: Moderate 41 of 220 days2007: Unhealthy for Sensitive Groups 8 of 220 days2008: Good 184 of 214 days2008: Moderate 28 of 214 days2008: Unhealthy for Sensitive Groups 2 of 214 days2009: Good 190 of 222 days2009: Moderate 32 of 222 days2010: Good 205 of 230 days2010: Moderate 25 of 230 days20102011: Good 199 of 223 days2011: Moderate 24 of 223 days2012: Good 194 of 222 days2012: Moderate 27 of 222 days2012: Unhealthy for Sensitive Groups 1 of 222 days2013: Good 203 of 222 days2013: Moderate 19 of 222 days2014: Good 186 of 208 days2014: Moderate 21 of 208 days2014: Unhealthy for Sensitive Groups 1 of 208 days2015: Good 186 of 204 days2015: Moderate 18 of 204 days20152016: Good 189 of 205 days2016: Moderate 16 of 205 days2017: Good 294 of 319 days2017: Moderate 25 of 319 days2018: Good 298 of 360 days2018: Moderate 62 of 360 days2019: Good 320 of 362 days2019: Moderate 42 of 362 days2020: Good 327 of 366 days2020: Moderate 39 of 366 days20202021: Good 297 of 363 days2021: Moderate 63 of 363 days2021: Unhealthy for Sensitive Groups 3 of 363 days2022: Good 329 of 363 days2022: Moderate 34 of 363 days2023: Good 247 of 340 days2023: Moderate 81 of 340 days2023: Unhealthy for Sensitive Groups 10 of 340 days2023: Unhealthy 2 of 340 days2024: Good 197 of 204 days2024: Moderate 7 of 204 days2025: Good 183 of 199 days2025: Moderate 15 of 199 days2025: Unhealthy for Sensitive Groups 1 of 199 days2025
  • 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 year0501001981: 90th percentile AQI 541982: 90th percentile AQI 671992: 90th percentile AQI 311993: 90th percentile AQI 451994: 90th percentile AQI 431995: 90th percentile AQI 481996: 90th percentile AQI 471997: 90th percentile AQI 461998: 90th percentile AQI 491999: 90th percentile AQI 592000: 90th percentile AQI 512001: 90th percentile AQI 542002: 90th percentile AQI 552003: 90th percentile AQI 612004: 90th percentile AQI 542005: 90th percentile AQI 742006: 90th percentile AQI 612007: 90th percentile AQI 642008: 90th percentile AQI 542009: 90th percentile AQI 542010: 90th percentile AQI 512011: 90th percentile AQI 512012: 90th percentile AQI 542013: 90th percentile AQI 502014: 90th percentile AQI 512015: 90th percentile AQI 482016: 90th percentile AQI 452017: 90th percentile AQI 492018: 90th percentile AQI 572019: 90th percentile AQI 522020: 90th percentile AQI 512021: 90th percentile AQI 572022: 90th percentile AQI 502023: 90th percentile AQI 752024: 90th percentile AQI 462025: 90th percentile AQI 491981: Median AQI 351982: Median AQI 341992: Median AQI 71993: Median AQI 311994: Median AQI 301995: Median AQI 311996: Median AQI 331997: Median AQI 321998: Median AQI 331999: Median AQI 372000: Median AQI 352001: Median AQI 362002: Median AQI 322003: Median AQI 402004: Median AQI 392005: Median AQI 412006: Median AQI 402007: Median AQI 402008: Median AQI 372009: Median AQI 372010: Median AQI 372011: Median AQI 362012: Median AQI 362013: Median AQI 372014: Median AQI 352015: Median AQI 342016: Median AQI 322017: Median AQI 342018: Median AQI 392019: Median AQI 312020: Median AQI 332021: Median AQI 342022: Median AQI 332023: Median AQI 392024: Median AQI 372025: Median AQI 3619811995200020052010201520202025
  • 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.

PollutantDays as main pollutantShare of monitored days
Ozone199100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20251991831510003649105Ozone
202420419770000374693Ozone
202334024781102003975168PM2.5
2022363329340000335068PM2.5
20213632976330003457148PM2.5
2020366327390000335184PM2.5
2019362320420000315291PM2.5
20183602986200003957100PM2.5
2017319294250000344980Ozone
2016205189160000324577Ozone
2015204186180000344884Ozone
20142081862110003551112Ozone
2013222203190000375080Ozone
20122221942710003654108Ozone
2011223199240000365197Ozone
2010230205250000375197Ozone
2009222190320000375484Ozone
20082141842820003754115Ozone
20072201714180004064150Ozone
2006211170410000406197Ozone
20052101564950004174129Ozone
20042412093110003954115Ozone
20032992405540004061119Ozone
2002276241350000325597Ozone
20012141783330003654112Ozone
20002101842420003551122Ozone
19992982504071003759154Ozone
19983653323030003349136Ozone
19973593391910003246105Ozone
19963613392020003347122Ozone
19953653352820003148126Ozone
1994361350110000304387Ozone
19933643441640003145119Ozone
199258580000073134PM10
19821561322130003467136Ozone
19811671471820003554115Ozone

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 2025

All monitored counties in Wisconsin

Source: U.S. EPA AirData, “Annual AQI by County” files for 1981–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem