EnviroNearby

Columbia County, Wisconsin air quality history

Daily Air Quality Index summaries from EPA monitors in Columbia, Wisconsin, 1980–2025.

85%
Good days in 2025
40
Median daily AQI, 2025
1
Days above 100 in 2025
198
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Columbia, Wisconsin on 198 days. 168 of those days (85%) were in the Good range, and the median daily AQI was 40. That median is about the same as the typical monitored county in Wisconsin (median 38 across 29 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 198 days. Across the years with fuller monitoring, the share of Good days rose: an average of 74% in 1980–1982 versus 81% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (198 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.

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%1980: Good 169 of 302 days1980: Moderate 89 of 302 days1980: Unhealthy for Sensitive Groups 27 of 302 days1980: Unhealthy 12 of 302 days1980: Very Unhealthy 5 of 302 days19801981: Good 301 of 359 days1981: Moderate 45 of 359 days1981: Unhealthy for Sensitive Groups 12 of 359 days1981: Unhealthy 1 of 359 days1982: Good 298 of 360 days1982: Moderate 52 of 360 days1982: Unhealthy for Sensitive Groups 8 of 360 days1982: Unhealthy 2 of 360 days1983: Good 314 of 365 days1983: Moderate 35 of 365 days1983: Unhealthy for Sensitive Groups 13 of 365 days1983: Unhealthy 3 of 365 days1984: Good 328 of 366 days1984: Moderate 34 of 366 days1984: Unhealthy for Sensitive Groups 3 of 366 days1984: Unhealthy 1 of 366 days1985: Good 326 of 363 days1985: Moderate 30 of 363 days1985: Unhealthy for Sensitive Groups 7 of 363 days19851986: Good 314 of 365 days1986: Moderate 44 of 365 days1986: Unhealthy for Sensitive Groups 7 of 365 days1987: Good 297 of 364 days1987: Moderate 47 of 364 days1987: Unhealthy for Sensitive Groups 18 of 364 days1987: Unhealthy 2 of 364 days1988: Good 270 of 355 days1988: Moderate 41 of 355 days1988: Unhealthy for Sensitive Groups 23 of 355 days1988: Unhealthy 12 of 355 days1988: Very Unhealthy 9 of 355 days1989: Good 222 of 304 days1989: Moderate 56 of 304 days1989: Unhealthy for Sensitive Groups 24 of 304 days1989: Unhealthy 2 of 304 days1990: Good 303 of 341 days1990: Moderate 32 of 341 days1990: Unhealthy for Sensitive Groups 6 of 341 days19901991: Good 243 of 304 days1991: Moderate 43 of 304 days1991: Unhealthy for Sensitive Groups 15 of 304 days1991: Unhealthy 3 of 304 days1992: Good 166 of 203 days1992: Moderate 24 of 203 days1992: Unhealthy for Sensitive Groups 12 of 203 days1992: Unhealthy 1 of 203 days1993: Good 205 of 212 days1993: Moderate 5 of 212 days1993: Unhealthy for Sensitive Groups 2 of 212 days1994: Good 190 of 214 days1994: Moderate 22 of 214 days1994: Unhealthy for Sensitive Groups 2 of 214 days1995: Good 116 of 177 days1995: Moderate 42 of 177 days1995: Unhealthy for Sensitive Groups 13 of 177 days1995: Unhealthy 6 of 177 days19951996: Good 133 of 181 days1996: Moderate 34 of 181 days1996: Unhealthy for Sensitive Groups 12 of 181 days1996: Unhealthy 2 of 181 days1997: Good 132 of 184 days1997: Moderate 47 of 184 days1997: Unhealthy for Sensitive Groups 5 of 184 days1998: Good 124 of 183 days1998: Moderate 51 of 183 days1998: Unhealthy for Sensitive Groups 8 of 183 days1999: Good 129 of 183 days1999: Moderate 38 of 183 days1999: Unhealthy for Sensitive Groups 11 of 183 days1999: Unhealthy 5 of 183 days2000: Good 150 of 184 days2000: Moderate 29 of 184 days2000: Unhealthy for Sensitive Groups 4 of 184 days2000: Unhealthy 1 of 184 days20002001: Good 138 of 183 days2001: Moderate 37 of 183 days2001: Unhealthy for Sensitive Groups 7 of 183 days2001: Unhealthy 1 of 183 days2002: Good 124 of 182 days2002: Moderate 45 of 182 days2002: Unhealthy for Sensitive Groups 11 of 182 days2002: Unhealthy 2 of 182 days2003: Good 115 of 184 days2003: Moderate 56 of 184 days2003: Unhealthy for Sensitive Groups 13 of 184 days2004: Good 161 of 183 days2004: Moderate 21 of 183 days2004: Unhealthy for Sensitive Groups 1 of 183 days2005: Good 122 of 185 days2005: Moderate 50 of 185 days2005: Unhealthy for Sensitive Groups 13 of 185 days20052006: Good 159 of 185 days2006: Moderate 25 of 185 days2006: Unhealthy for Sensitive Groups 1 of 185 days2007: Good 137 of 194 days2007: Moderate 48 of 194 days2007: Unhealthy for Sensitive Groups 8 of 194 days2007: Unhealthy 1 of 194 days2008: Good 164 of 196 days2008: Moderate 32 of 196 days2009: Good 173 of 197 days2009: Moderate 24 of 197 days2010: Good 167 of 188 days2010: Moderate 21 of 188 days20102011: Good 171 of 204 days2011: Moderate 32 of 204 days2011: Unhealthy for Sensitive Groups 1 of 204 days2012: Good 154 of 220 days2012: Moderate 54 of 220 days2012: Unhealthy for Sensitive Groups 11 of 220 days2012: Unhealthy 1 of 220 days2013: Good 178 of 218 days2013: Moderate 39 of 218 days2013: Unhealthy for Sensitive Groups 1 of 218 days2014: Good 176 of 203 days2014: Moderate 25 of 203 days2014: Unhealthy for Sensitive Groups 2 of 203 days2015: Good 192 of 214 days2015: Moderate 22 of 214 days20152016: Good 176 of 199 days2016: Moderate 20 of 199 days2016: Unhealthy for Sensitive Groups 3 of 199 days2017: Good 211 of 237 days2017: Moderate 26 of 237 days2018: Good 217 of 246 days2018: Moderate 28 of 246 days2018: Unhealthy for Sensitive Groups 1 of 246 days2019: Good 184 of 192 days2019: Moderate 8 of 192 days2020: Good 187 of 203 days2020: Moderate 12 of 203 days2020: Unhealthy for Sensitive Groups 4 of 203 days20202021: Good 181 of 208 days2021: Moderate 27 of 208 days2022: Good 191 of 202 days2022: Moderate 11 of 202 days2023: Good 133 of 203 days2023: Moderate 52 of 203 days2023: Unhealthy for Sensitive Groups 16 of 203 days2023: Unhealthy 2 of 203 days2024: Good 186 of 203 days2024: Moderate 17 of 203 days2025: Good 168 of 198 days2025: Moderate 29 of 198 days2025: Unhealthy for Sensitive Groups 1 of 198 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 year0501001501980: 90th percentile AQI 1121981: 90th percentile AQI 671982: 90th percentile AQI 671983: 90th percentile AQI 671984: 90th percentile AQI 511985: 90th percentile AQI 511986: 90th percentile AQI 611987: 90th percentile AQI 841988: 90th percentile AQI 1151989: 90th percentile AQI 931990: 90th percentile AQI 541991: 90th percentile AQI 801992: 90th percentile AQI 771993: 90th percentile AQI 451994: 90th percentile AQI 511995: 90th percentile AQI 1011996: 90th percentile AQI 901997: 90th percentile AQI 801998: 90th percentile AQI 801999: 90th percentile AQI 972000: 90th percentile AQI 672001: 90th percentile AQI 842002: 90th percentile AQI 932003: 90th percentile AQI 972004: 90th percentile AQI 542005: 90th percentile AQI 902006: 90th percentile AQI 582007: 90th percentile AQI 802008: 90th percentile AQI 582009: 90th percentile AQI 512010: 90th percentile AQI 512011: 90th percentile AQI 582012: 90th percentile AQI 842013: 90th percentile AQI 612014: 90th percentile AQI 542015: 90th percentile AQI 512016: 90th percentile AQI 582017: 90th percentile AQI 512018: 90th percentile AQI 512019: 90th percentile AQI 462020: 90th percentile AQI 482021: 90th percentile AQI 542022: 90th percentile AQI 462023: 90th percentile AQI 932024: 90th percentile AQI 502025: 90th percentile AQI 581980: Median AQI 461981: Median AQI 351982: Median AQI 371983: Median AQI 331984: Median AQI 331985: Median AQI 331986: Median AQI 331987: Median AQI 331988: Median AQI 361989: Median AQI 411990: Median AQI 321991: Median AQI 351992: Median AQI 371993: Median AQI 331994: Median AQI 371995: Median AQI 441996: Median AQI 441997: Median AQI 441998: Median AQI 451999: Median AQI 442000: Median AQI 422001: Median AQI 442002: Median AQI 442003: Median AQI 472004: Median AQI 382005: Median AQI 442006: Median AQI 412007: Median AQI 442008: Median AQI 422009: Median AQI 382010: Median AQI 402011: Median AQI 402012: Median AQI 432013: Median AQI 412014: Median AQI 402015: Median AQI 402016: Median AQI 382017: Median AQI 392018: Median AQI 392019: Median AQI 372020: Median AQI 382021: Median AQI 402022: Median AQI 382023: Median AQI 442024: Median AQI 382025: Median AQI 401980198519901995200020052010201520202025
  • 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
Ozone198100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20251981682910004058108Ozone
2024203186170000385093Ozone
202320313352162004493159Ozone
2022202191110000384680Ozone
20212081812700004054100Ozone
20202031871240003848115Ozone
201919218480000374671Ozone
20182462172810003951122Ozone
2017237211260000395193Ozone
20161991762030003858108Ozone
2015214192220000405180Ozone
20142031762520004054112Ozone
20132181783910004161101Ozone
201222015454111004384151Ozone
20112041713210004058101Ozone
2010188167210000405193Ozone
2009197173240000385187Ozone
20081961643200004258100Ozone
20071941374881004480151Ozone
20061851592510004158105Ozone
200518512250130004490150Ozone
20041831612110003854115Ozone
200318411556130004797143Ozone
200218212445112004493154Ozone
20011831383771004484151Ozone
20001841502941004267151Ozone
199918312938115004497172Ozone
19981831245180004580133Ozone
19971841324750004480150Ozone
199618113334122004490174Ozone
1995177116421360044101185Ozone
19942141902220003751112Ozone
1993212205520003345140Ozone
199220316624121003777154Ozone
199130424343153003580172Ozone
19903413033260003254133Ozone
198930422256242004193195Ozone
19883552704123129036115217Ozone
198736429747182003384177Ozone
19863653144470003361122Ozone
19853633263070003351150Ozone
19843663283431003351161Ozone
198336531435133003367185Ozone
19823602985282003767154Ozone
198135930145121003567159Ozone
19803021698927125046112233Ozone

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 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