EnviroNearby

Peoria County, Illinois air quality history

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

60%
Good days in 2025
45
Median daily AQI, 2025
4
Days above 100 in 2025
357
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Peoria, Illinois on 357 days. 214 of those days (60%) were in the Good range, and the median daily AQI was 45. That median is higher than 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 fine particles (PM2.5) on 235 days. Across the years with fuller monitoring, the share of Good days fell: an average of 79% in 1980–1982 versus 61% 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 302 of 358 days1980: Moderate 41 of 358 days1980: Unhealthy for Sensitive Groups 14 of 358 days1980: Unhealthy 1 of 358 days19801981: Good 267 of 358 days1981: Moderate 74 of 358 days1981: Unhealthy for Sensitive Groups 16 of 358 days1981: Unhealthy 1 of 358 days1982: Good 278 of 363 days1982: Moderate 80 of 363 days1982: Unhealthy for Sensitive Groups 4 of 363 days1982: Unhealthy 1 of 363 days1983: Good 287 of 365 days1983: Moderate 54 of 365 days1983: Unhealthy for Sensitive Groups 18 of 365 days1983: Unhealthy 6 of 365 days1984: Good 285 of 366 days1984: Moderate 66 of 366 days1984: Unhealthy for Sensitive Groups 15 of 366 days1985: Good 315 of 365 days1985: Moderate 46 of 365 days1985: Unhealthy for Sensitive Groups 4 of 365 days19851986: Good 297 of 365 days1986: Moderate 59 of 365 days1986: Unhealthy for Sensitive Groups 8 of 365 days1986: Unhealthy 1 of 365 days1987: Good 256 of 365 days1987: Moderate 80 of 365 days1987: Unhealthy for Sensitive Groups 22 of 365 days1987: Unhealthy 6 of 365 days1987: Very Unhealthy 1 of 365 days1988: Good 254 of 366 days1988: Moderate 65 of 366 days1988: Unhealthy for Sensitive Groups 34 of 366 days1988: Unhealthy 13 of 366 days1989: Good 282 of 364 days1989: Moderate 65 of 364 days1989: Unhealthy for Sensitive Groups 15 of 364 days1989: Unhealthy 2 of 364 days1990: Good 285 of 365 days1990: Moderate 70 of 365 days1990: Unhealthy for Sensitive Groups 10 of 365 days19901991: Good 266 of 361 days1991: Moderate 82 of 361 days1991: Unhealthy for Sensitive Groups 11 of 361 days1991: Unhealthy 2 of 361 days1992: Good 260 of 366 days1992: Moderate 95 of 366 days1992: Unhealthy for Sensitive Groups 9 of 366 days1992: Unhealthy 2 of 366 days1993: Good 305 of 364 days1993: Moderate 56 of 364 days1993: Unhealthy for Sensitive Groups 3 of 364 days1994: Good 292 of 365 days1994: Moderate 60 of 365 days1994: Unhealthy for Sensitive Groups 12 of 365 days1994: Unhealthy 1 of 365 days1995: Good 277 of 365 days1995: Moderate 68 of 365 days1995: Unhealthy for Sensitive Groups 14 of 365 days1995: Unhealthy 6 of 365 days19951996: Good 315 of 366 days1996: Moderate 39 of 366 days1996: Unhealthy for Sensitive Groups 12 of 366 days1997: Good 307 of 365 days1997: Moderate 51 of 365 days1997: Unhealthy for Sensitive Groups 7 of 365 days1998: Good 297 of 365 days1998: Moderate 58 of 365 days1998: Unhealthy for Sensitive Groups 9 of 365 days1998: Unhealthy 1 of 365 days1999: Good 268 of 365 days1999: Moderate 83 of 365 days1999: Unhealthy for Sensitive Groups 11 of 365 days1999: Unhealthy 3 of 365 days2000: Good 245 of 366 days2000: Moderate 114 of 366 days2000: Unhealthy for Sensitive Groups 7 of 366 days20002001: Good 235 of 365 days2001: Moderate 119 of 365 days2001: Unhealthy for Sensitive Groups 11 of 365 days2002: Good 241 of 365 days2002: Moderate 104 of 365 days2002: Unhealthy for Sensitive Groups 17 of 365 days2002: Unhealthy 3 of 365 days2003: Good 245 of 365 days2003: Moderate 110 of 365 days2003: Unhealthy for Sensitive Groups 10 of 365 days2004: Good 277 of 366 days2004: Moderate 87 of 366 days2004: Unhealthy for Sensitive Groups 2 of 366 days2005: Good 228 of 365 days2005: Moderate 121 of 365 days2005: Unhealthy for Sensitive Groups 16 of 365 days20052006: Good 261 of 365 days2006: Moderate 100 of 365 days2006: Unhealthy for Sensitive Groups 4 of 365 days2007: Good 113 of 365 days2007: Moderate 233 of 365 days2007: Unhealthy for Sensitive Groups 19 of 365 days2008: Good 144 of 366 days2008: Moderate 222 of 366 days2009: Good 149 of 365 days2009: Moderate 213 of 365 days2009: Unhealthy for Sensitive Groups 3 of 365 days2010: Good 114 of 365 days2010: Moderate 248 of 365 days2010: Unhealthy for Sensitive Groups 3 of 365 days20102011: Good 104 of 365 days2011: Moderate 258 of 365 days2011: Unhealthy for Sensitive Groups 2 of 365 days2011: Unhealthy 1 of 365 days2012: Good 144 of 366 days2012: Moderate 201 of 366 days2012: Unhealthy for Sensitive Groups 21 of 366 days2013: Good 166 of 365 days2013: Moderate 199 of 365 days2014: Good 204 of 365 days2014: Moderate 161 of 365 days2015: Good 201 of 365 days2015: Moderate 164 of 365 days20152016: Good 206 of 366 days2016: Moderate 158 of 366 days2016: Unhealthy for Sensitive Groups 2 of 366 days2017: Good 172 of 365 days2017: Moderate 190 of 365 days2017: Unhealthy for Sensitive Groups 3 of 365 days2018: Good 189 of 365 days2018: Moderate 173 of 365 days2018: Unhealthy for Sensitive Groups 3 of 365 days2019: Good 236 of 364 days2019: Moderate 126 of 364 days2019: Unhealthy for Sensitive Groups 2 of 364 days2020: Good 247 of 364 days2020: Moderate 116 of 364 days2020: Unhealthy for Sensitive Groups 1 of 364 days20202021: Good 181 of 361 days2021: Moderate 179 of 361 days2021: Unhealthy for Sensitive Groups 1 of 361 days2022: Good 181 of 319 days2022: Moderate 138 of 319 days2023: Good 187 of 340 days2023: Moderate 131 of 340 days2023: Unhealthy for Sensitive Groups 21 of 340 days2023: Unhealthy 1 of 340 days2024: Good 236 of 344 days2024: Moderate 108 of 344 days2025: Good 214 of 357 days2025: Moderate 139 of 357 days2025: Unhealthy for Sensitive Groups 2 of 357 days2025: Unhealthy 2 of 357 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 711981: 90th percentile AQI 741982: 90th percentile AQI 721983: 90th percentile AQI 841984: 90th percentile AQI 741985: 90th percentile AQI 611986: 90th percentile AQI 671987: 90th percentile AQI 931988: 90th percentile AQI 1121989: 90th percentile AQI 841990: 90th percentile AQI 671991: 90th percentile AQI 651992: 90th percentile AQI 661993: 90th percentile AQI 541994: 90th percentile AQI 671995: 90th percentile AQI 871996: 90th percentile AQI 641997: 90th percentile AQI 641998: 90th percentile AQI 671999: 90th percentile AQI 772000: 90th percentile AQI 722001: 90th percentile AQI 802002: 90th percentile AQI 812003: 90th percentile AQI 772004: 90th percentile AQI 642005: 90th percentile AQI 852006: 90th percentile AQI 672007: 90th percentile AQI 872008: 90th percentile AQI 742009: 90th percentile AQI 702010: 90th percentile AQI 752011: 90th percentile AQI 702012: 90th percentile AQI 842013: 90th percentile AQI 652014: 90th percentile AQI 662015: 90th percentile AQI 662016: 90th percentile AQI 622017: 90th percentile AQI 662018: 90th percentile AQI 672019: 90th percentile AQI 622020: 90th percentile AQI 612021: 90th percentile AQI 652022: 90th percentile AQI 652023: 90th percentile AQI 772024: 90th percentile AQI 602025: 90th percentile AQI 661980: Median AQI 311981: Median AQI 381982: Median AQI 391983: Median AQI 371984: Median AQI 381985: Median AQI 341986: Median AQI 331987: Median AQI 441988: Median AQI 401989: Median AQI 381990: Median AQI 381991: Median AQI 431992: Median AQI 441993: Median AQI 391994: Median AQI 401995: Median AQI 401996: Median AQI 361997: Median AQI 381998: Median AQI 391999: Median AQI 412000: Median AQI 402001: Median AQI 432002: Median AQI 412003: Median AQI 412004: Median AQI 382005: Median AQI 432006: Median AQI 392007: Median AQI 572008: Median AQI 542009: Median AQI 522010: Median AQI 562011: Median AQI 562012: Median AQI 542013: Median AQI 522014: Median AQI 462015: Median AQI 472016: Median AQI 482017: Median AQI 512018: Median AQI 492019: Median AQI 442020: Median AQI 442021: Median AQI 502022: Median AQI 482023: Median AQI 482024: Median AQI 442025: Median AQI 451980198519901995200020052010201520202025
  • 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
Fine particles (PM2.5)23566%
Ozone12234%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202535721413922004566154PM2.5
202434423610800004460100PM2.5
2023340187131211004877151Ozone
202231918113800004865100PM2.5
202136118117910005065101PM2.5
202036424711610004461115PM2.5
201936423612620004462101PM2.5
201836518917330004967101PM2.5
201736517219030005166115PM2.5
201636620615820004862108PM2.5
20153652011640000476690PM2.5
201436520416100004666100PM2.5
20133651661990000526597PM2.5
2012366144201210005484140PM2.5
201136510425821005670159PM2.5
201036511424830005675105PM2.5
200936514921330005270105PM2.5
200836614422200005474100PM2.5
2007365113233190005787136PM2.5
200636526110040003967108Ozone
2005365228121160004385133Ozone
20043662778720003864118Ozone
2003365245110100004177129Ozone
2002365241104173004181169Ozone
2001365235119110004380147Ozone
200036624511470004072115Ozone
199936526883113004177166Ozone
19983652975891003967154Ozone
19973653075170003864143Ozone
199636631539120003664147Ozone
199536527768146004087159Ozone
199436529260121004067154Ozone
19933643055630003954126CO
19923662609592004466159CO
199136126682112004365197CO
199036528570100003867126Ozone
198936428265152003884159Ozone
19883662546534130040112187Ozone
198736525680226104493212CO
19863652975981003367151Ozone
19853653154640003461136Ozone
198436628566150003874150Ozone
198336528754186003784172Ozone
19823632788041003972151Ozone
198135826774161003874169Ozone
198035830241141003171154Ozone

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