EnviroNearby

Champaign County, Illinois air quality history

Daily Air Quality Index summaries from EPA monitors in Champaign, Illinois, 1980–2025.

66%
Good days in 2025
43
Median daily AQI, 2025
4
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Champaign, Illinois on 365 days. 240 of those days (66%) were in the Good range, and the median daily AQI was 43. That median is about the same as the typical monitored county in Illinois (median 42 across 23 counties), and higher 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 fell: an average of 84% in 1980–1982 versus 63% in 2023–2025.

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 240 of 285 days1980: Moderate 33 of 285 days1980: Unhealthy for Sensitive Groups 12 of 285 days19801981: Good 281 of 325 days1981: Moderate 36 of 325 days1981: Unhealthy for Sensitive Groups 8 of 325 days1982: Good 266 of 325 days1982: Moderate 50 of 325 days1982: Unhealthy for Sensitive Groups 9 of 325 days1983: Good 276 of 357 days1983: Moderate 55 of 357 days1983: Unhealthy for Sensitive Groups 20 of 357 days1983: Unhealthy 6 of 357 days1984: Good 216 of 280 days1984: Moderate 47 of 280 days1984: Unhealthy for Sensitive Groups 15 of 280 days1984: Unhealthy 2 of 280 days1985: Good 283 of 352 days1985: Moderate 58 of 352 days1985: Unhealthy for Sensitive Groups 9 of 352 days1985: Unhealthy 2 of 352 days19851986: Good 287 of 343 days1986: Moderate 46 of 343 days1986: Unhealthy for Sensitive Groups 10 of 343 days1987: Good 293 of 357 days1987: Moderate 49 of 357 days1987: Unhealthy for Sensitive Groups 13 of 357 days1987: Unhealthy 2 of 357 days1988: Good 265 of 343 days1988: Moderate 43 of 343 days1988: Unhealthy for Sensitive Groups 26 of 343 days1988: Unhealthy 9 of 343 days1989: Good 278 of 356 days1989: Moderate 47 of 356 days1989: Unhealthy for Sensitive Groups 31 of 356 days1990: Good 321 of 360 days1990: Moderate 33 of 360 days1990: Unhealthy for Sensitive Groups 6 of 360 days19901991: Good 288 of 329 days1991: Moderate 35 of 329 days1991: Unhealthy for Sensitive Groups 6 of 329 days1992: Good 327 of 356 days1992: Moderate 25 of 356 days1992: Unhealthy for Sensitive Groups 3 of 356 days1992: Unhealthy 1 of 356 days1993: Good 339 of 353 days1993: Moderate 13 of 353 days1993: Unhealthy for Sensitive Groups 1 of 353 days1994: Good 281 of 365 days1994: Moderate 67 of 365 days1994: Unhealthy for Sensitive Groups 16 of 365 days1994: Unhealthy 1 of 365 days1995: Good 285 of 364 days1995: Moderate 55 of 364 days1995: Unhealthy for Sensitive Groups 21 of 364 days1995: Unhealthy 3 of 364 days19951996: Good 308 of 366 days1996: Moderate 46 of 366 days1996: Unhealthy for Sensitive Groups 10 of 366 days1996: Unhealthy 2 of 366 days1997: Good 308 of 362 days1997: Moderate 46 of 362 days1997: Unhealthy for Sensitive Groups 8 of 362 days1998: Good 289 of 363 days1998: Moderate 61 of 363 days1998: Unhealthy for Sensitive Groups 11 of 363 days1998: Unhealthy 2 of 363 days1999: Good 246 of 365 days1999: Moderate 81 of 365 days1999: Unhealthy for Sensitive Groups 31 of 365 days1999: Unhealthy 6 of 365 days1999: Very Unhealthy 1 of 365 days2000: Good 246 of 366 days2000: Moderate 105 of 366 days2000: Unhealthy for Sensitive Groups 13 of 366 days2000: Unhealthy 2 of 366 days20002001: Good 236 of 365 days2001: Moderate 109 of 365 days2001: Unhealthy for Sensitive Groups 20 of 365 days2002: Good 221 of 365 days2002: Moderate 114 of 365 days2002: Unhealthy for Sensitive Groups 23 of 365 days2002: Unhealthy 7 of 365 days2003: Good 233 of 365 days2003: Moderate 110 of 365 days2003: Unhealthy for Sensitive Groups 21 of 365 days2003: Unhealthy 1 of 365 days2004: Good 253 of 366 days2004: Moderate 109 of 366 days2004: Unhealthy for Sensitive Groups 4 of 366 days2005: Good 224 of 365 days2005: Moderate 119 of 365 days2005: Unhealthy for Sensitive Groups 22 of 365 days20052006: Good 249 of 365 days2006: Moderate 113 of 365 days2006: Unhealthy for Sensitive Groups 3 of 365 days2007: Good 235 of 365 days2007: Moderate 116 of 365 days2007: Unhealthy for Sensitive Groups 14 of 365 days2008: Good 274 of 366 days2008: Moderate 92 of 366 days2009: Good 273 of 365 days2009: Moderate 92 of 365 days2010: Good 280 of 352 days2010: Moderate 72 of 352 days20102011: Good 256 of 348 days2011: Moderate 85 of 348 days2011: Unhealthy for Sensitive Groups 6 of 348 days2011: Unhealthy 1 of 348 days2012: Good 273 of 366 days2012: Moderate 85 of 366 days2012: Unhealthy for Sensitive Groups 8 of 366 days2013: Good 294 of 365 days2013: Moderate 71 of 365 days2014: Good 277 of 365 days2014: Moderate 87 of 365 days2014: Unhealthy for Sensitive Groups 1 of 365 days2015: Good 217 of 365 days2015: Moderate 148 of 365 days20152016: Good 254 of 366 days2016: Moderate 112 of 366 days2017: Good 233 of 365 days2017: Moderate 131 of 365 days2017: Unhealthy for Sensitive Groups 1 of 365 days2018: Good 209 of 365 days2018: Moderate 152 of 365 days2018: Unhealthy for Sensitive Groups 4 of 365 days2019: Good 225 of 365 days2019: Moderate 140 of 365 days2020: Good 250 of 366 days2020: Moderate 114 of 366 days2020: Unhealthy for Sensitive Groups 2 of 366 days20202021: Good 236 of 365 days2021: Moderate 129 of 365 days2022: Good 223 of 365 days2022: Moderate 141 of 365 days2022: Unhealthy for Sensitive Groups 1 of 365 days2023: Good 196 of 365 days2023: Moderate 156 of 365 days2023: Unhealthy for Sensitive Groups 11 of 365 days2023: Unhealthy 1 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 250 of 366 days2024: Moderate 116 of 366 days2025: Good 240 of 365 days2025: Moderate 121 of 365 days2025: Unhealthy for Sensitive Groups 4 of 365 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 741981: 90th percentile AQI 641982: 90th percentile AQI 711983: 90th percentile AQI 871984: 90th percentile AQI 871985: 90th percentile AQI 711986: 90th percentile AQI 671987: 90th percentile AQI 671988: 90th percentile AQI 1011989: 90th percentile AQI 971990: 90th percentile AQI 511991: 90th percentile AQI 581992: 90th percentile AQI 481993: 90th percentile AQI 441994: 90th percentile AQI 801995: 90th percentile AQI 901996: 90th percentile AQI 711997: 90th percentile AQI 641998: 90th percentile AQI 671999: 90th percentile AQI 1012000: 90th percentile AQI 802001: 90th percentile AQI 872002: 90th percentile AQI 932003: 90th percentile AQI 842004: 90th percentile AQI 712005: 90th percentile AQI 872006: 90th percentile AQI 712007: 90th percentile AQI 802008: 90th percentile AQI 632009: 90th percentile AQI 632010: 90th percentile AQI 572011: 90th percentile AQI 672012: 90th percentile AQI 772013: 90th percentile AQI 602014: 90th percentile AQI 642015: 90th percentile AQI 632016: 90th percentile AQI 612017: 90th percentile AQI 612018: 90th percentile AQI 652019: 90th percentile AQI 642020: 90th percentile AQI 612021: 90th percentile AQI 632022: 90th percentile AQI 622023: 90th percentile AQI 702024: 90th percentile AQI 602025: 90th percentile AQI 661980: Median AQI 281981: Median AQI 311982: Median AQI 331983: Median AQI 331984: Median AQI 371985: Median AQI 341986: Median AQI 321987: Median AQI 311988: Median AQI 321989: Median AQI 311990: Median AQI 311991: Median AQI 311992: Median AQI 301993: Median AQI 281994: Median AQI 341995: Median AQI 331996: Median AQI 321997: Median AQI 311998: Median AQI 341999: Median AQI 432000: Median AQI 412001: Median AQI 422002: Median AQI 442003: Median AQI 442004: Median AQI 422005: Median AQI 442006: Median AQI 412007: Median AQI 432008: Median AQI 392009: Median AQI 392010: Median AQI 352011: Median AQI 402012: Median AQI 412013: Median AQI 392014: Median AQI 382015: Median AQI 462016: Median AQI 432017: Median AQI 452018: Median AQI 472019: Median AQI 452020: Median AQI 442021: Median AQI 442022: Median AQI 442023: Median AQI 482024: Median AQI 442025: Median AQI 431980198519901995200020052010201520202025
  • 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
Ozone19955%
Fine particles (PM2.5)16645%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536524012140004366138Ozone
202436625011600004460100Ozone
2023365196156111104870277PM2.5
202236522314110004462126PM2.5
20213652361290000446399PM2.5
202036625011420004461126PM2.5
201936522514000004564100PM2.5
201836520915240004765112PM2.5
201736523313110004561105PM2.5
201636625411200004361100Ozone
20153652171480000466390PM2.5
20143652778710003864101Ozone
20133652947100003960100Ozone
20123662738580004177136Ozone
20113482568561004067156Ozone
2010352280720000355788Ozone
20093652739200003963100Ozone
2008366274920000396397Ozone
2007365235116140004380140Ozone
200636524911330004171129Ozone
2005365224119220004487143Ozone
200436625310940004271120Ozone
2003365233110211004484154Ozone
2002365221114237004493197Ozone
2001365236109200004287136Ozone
2000366246105132004180161Ozone
1999365246813161043101201Ozone
199836328961112003467161Ozone
19973623084680003164140Ozone
199636630846102003271166Ozone
199536428555213003390159Ozone
199436528167161003480166Ozone
19933533391310002844115Ozone
19923563272531003048156Ozone
19913292883560003158136Ozone
19903603213360003151133Ozone
198935627847310003197147Ozone
1988343265432690032101169Ozone
198735729349132003167177Ozone
198634328746100003267136Ozone
19853522835892003471164Ozone
198428021647152003787161Ozone
198335727655206003387187Ozone
19823252665090003371129Ozone
19813252813680003164133Ozone
198028524033120002874133Ozone

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 Illinois with a similar median AQI in 2025

All monitored counties in Illinois

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