EnviroNearby

Effingham County, Illinois air quality history

Daily Air Quality Index summaries from EPA monitors in Effingham, Illinois, 1981–2025.

95%
Good days in 2025
35
Median daily AQI, 2025
0
Days above 100 in 2025
242
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Effingham, Illinois on 242 days. 231 of those days (95%) were in the Good range, and the median daily AQI was 35. That median is lower than the typical monitored county in Illinois (median 42 across 23 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 242 days. Across the years with fuller monitoring, the share of Good days rose: an average of 75% in 1982–1984 versus 87% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (242 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 (1981) 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 56 of 57 days1981: Moderate 1 of 57 days19811982: Good 219 of 283 days1982: Moderate 53 of 283 days1982: Unhealthy for Sensitive Groups 11 of 283 days1983: Good 251 of 336 days1983: Moderate 52 of 336 days1983: Unhealthy for Sensitive Groups 29 of 336 days1983: Unhealthy 4 of 336 days1984: Good 236 of 328 days1984: Moderate 55 of 328 days1984: Unhealthy for Sensitive Groups 34 of 328 days1984: Unhealthy 3 of 328 days1985: Good 267 of 358 days1985: Moderate 73 of 358 days1985: Unhealthy for Sensitive Groups 14 of 358 days1985: Unhealthy 4 of 358 days1986: Good 190 of 275 days1986: Moderate 64 of 275 days1986: Unhealthy for Sensitive Groups 19 of 275 days1986: Unhealthy 2 of 275 days19861987: Good 126 of 220 days1987: Moderate 66 of 220 days1987: Unhealthy for Sensitive Groups 26 of 220 days1987: Unhealthy 2 of 220 days1988: Good 101 of 222 days1988: Moderate 65 of 222 days1988: Unhealthy for Sensitive Groups 35 of 222 days1988: Unhealthy 20 of 222 days1988: Very Unhealthy 1 of 222 days1989: Good 118 of 212 days1989: Moderate 72 of 212 days1989: Unhealthy for Sensitive Groups 20 of 212 days1989: Unhealthy 2 of 212 days1990: Good 139 of 202 days1990: Moderate 45 of 202 days1990: Unhealthy for Sensitive Groups 18 of 202 days1991: Good 128 of 207 days1991: Moderate 59 of 207 days1991: Unhealthy for Sensitive Groups 18 of 207 days1991: Unhealthy 2 of 207 days19911992: Good 148 of 203 days1992: Moderate 45 of 203 days1992: Unhealthy for Sensitive Groups 9 of 203 days1992: Unhealthy 1 of 203 days1993: Good 188 of 232 days1993: Moderate 39 of 232 days1993: Unhealthy for Sensitive Groups 5 of 232 days1994: Good 144 of 225 days1994: Moderate 52 of 225 days1994: Unhealthy for Sensitive Groups 27 of 225 days1994: Unhealthy 2 of 225 days1995: Good 134 of 225 days1995: Moderate 68 of 225 days1995: Unhealthy for Sensitive Groups 18 of 225 days1995: Unhealthy 5 of 225 days1996: Good 164 of 225 days1996: Moderate 46 of 225 days1996: Unhealthy for Sensitive Groups 13 of 225 days1996: Unhealthy 2 of 225 days19961997: Good 171 of 237 days1997: Moderate 53 of 237 days1997: Unhealthy for Sensitive Groups 11 of 237 days1997: Unhealthy 2 of 237 days1998: Good 152 of 234 days1998: Moderate 70 of 234 days1998: Unhealthy for Sensitive Groups 11 of 234 days1998: Unhealthy 1 of 234 days1999: Good 148 of 235 days1999: Moderate 62 of 235 days1999: Unhealthy for Sensitive Groups 19 of 235 days1999: Unhealthy 6 of 235 days2000: Good 175 of 229 days2000: Moderate 47 of 229 days2000: Unhealthy for Sensitive Groups 7 of 229 days2001: Good 147 of 213 days2001: Moderate 59 of 213 days2001: Unhealthy for Sensitive Groups 7 of 213 days20012002: Good 153 of 213 days2002: Moderate 38 of 213 days2002: Unhealthy for Sensitive Groups 20 of 213 days2002: Unhealthy 2 of 213 days2003: Good 165 of 214 days2003: Moderate 47 of 214 days2003: Unhealthy for Sensitive Groups 2 of 214 days2004: Good 170 of 207 days2004: Moderate 35 of 207 days2004: Unhealthy for Sensitive Groups 2 of 207 days2005: Good 141 of 215 days2005: Moderate 67 of 215 days2005: Unhealthy for Sensitive Groups 7 of 215 days2006: Good 182 of 216 days2006: Moderate 32 of 216 days2006: Unhealthy for Sensitive Groups 2 of 216 days20062007: Good 150 of 223 days2007: Moderate 61 of 223 days2007: Unhealthy for Sensitive Groups 12 of 223 days2008: Good 189 of 212 days2008: Moderate 23 of 212 days2009: Good 206 of 240 days2009: Moderate 33 of 240 days2009: Unhealthy for Sensitive Groups 1 of 240 days2010: Good 157 of 195 days2010: Moderate 32 of 195 days2010: Unhealthy for Sensitive Groups 6 of 195 days2011: Good 175 of 211 days2011: Moderate 35 of 211 days2011: Unhealthy for Sensitive Groups 1 of 211 days20112012: Good 125 of 192 days2012: Moderate 58 of 192 days2012: Unhealthy for Sensitive Groups 8 of 192 days2012: Unhealthy 1 of 192 days2013: Good 184 of 213 days2013: Moderate 29 of 213 days2014: Good 187 of 212 days2014: Moderate 25 of 212 days2015: Good 184 of 203 days2015: Moderate 19 of 203 days2016: Good 181 of 214 days2016: Moderate 33 of 214 days20162017: Good 206 of 244 days2017: Moderate 35 of 244 days2017: Unhealthy for Sensitive Groups 3 of 244 days2018: Good 214 of 245 days2018: Moderate 30 of 245 days2018: Unhealthy for Sensitive Groups 1 of 245 days2019: Good 224 of 245 days2019: Moderate 21 of 245 days2020: Good 156 of 166 days2020: Moderate 10 of 166 days2021: Good 226 of 237 days2021: Moderate 11 of 237 days20212022: Good 215 of 239 days2022: Moderate 24 of 239 days2023: Good 182 of 242 days2023: Moderate 50 of 242 days2023: Unhealthy for Sensitive Groups 10 of 242 days2024: Good 217 of 240 days2024: Moderate 22 of 240 days2024: Unhealthy for Sensitive Groups 1 of 240 days2025: Good 231 of 242 days2025: Moderate 11 of 242 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 year0501001501981: 90th percentile AQI 401982: 90th percentile AQI 841983: 90th percentile AQI 1001984: 90th percentile AQI 1011985: 90th percentile AQI 871986: 90th percentile AQI 971987: 90th percentile AQI 1121988: 90th percentile AQI 1501989: 90th percentile AQI 1011990: 90th percentile AQI 1001991: 90th percentile AQI 1001992: 90th percentile AQI 801993: 90th percentile AQI 671994: 90th percentile AQI 1051995: 90th percentile AQI 1011996: 90th percentile AQI 871997: 90th percentile AQI 801998: 90th percentile AQI 871999: 90th percentile AQI 1012000: 90th percentile AQI 712001: 90th percentile AQI 872002: 90th percentile AQI 1012003: 90th percentile AQI 672004: 90th percentile AQI 642005: 90th percentile AQI 842006: 90th percentile AQI 582007: 90th percentile AQI 872008: 90th percentile AQI 512009: 90th percentile AQI 582010: 90th percentile AQI 742011: 90th percentile AQI 642012: 90th percentile AQI 902013: 90th percentile AQI 582014: 90th percentile AQI 512015: 90th percentile AQI 502016: 90th percentile AQI 542017: 90th percentile AQI 612018: 90th percentile AQI 512019: 90th percentile AQI 502020: 90th percentile AQI 482021: 90th percentile AQI 462022: 90th percentile AQI 512023: 90th percentile AQI 742024: 90th percentile AQI 502025: 90th percentile AQI 461981: Median AQI 251982: Median AQI 351983: Median AQI 351984: Median AQI 331985: Median AQI 361986: Median AQI 431987: Median AQI 461988: Median AQI 581989: Median AQI 481990: Median AQI 441991: Median AQI 451992: Median AQI 441993: Median AQI 411994: Median AQI 451995: Median AQI 461996: Median AQI 421997: Median AQI 421998: Median AQI 471999: Median AQI 452000: Median AQI 422001: Median AQI 442002: Median AQI 442003: Median AQI 422004: Median AQI 402005: Median AQI 442006: Median AQI 392007: Median AQI 452008: Median AQI 382009: Median AQI 412010: Median AQI 442011: Median AQI 432012: Median AQI 462013: Median AQI 412014: Median AQI 382015: Median AQI 402016: Median AQI 392017: Median AQI 432018: Median AQI 392019: Median AQI 402020: Median AQI 372021: Median AQI 372022: Median AQI 382023: Median AQI 442024: Median AQI 412025: Median AQI 351981198619911996200120062011201620212025
  • 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
Ozone242100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025242231110000354684Ozone
20242402172210004150101Ozone
202324218250100004474140Ozone
20222392152400003851100Ozone
2021237226110000374677Ozone
2020166156100000374884Ozone
2019245224210000405084Ozone
20182452143010003951112Ozone
20172442063530004361112Ozone
2016214181330000395493Ozone
2015203184190000405084Ozone
2014212187250000385190Ozone
2013213184290000415897Ozone
20121921255881004690166Ozone
20112111753510004364108Ozone
20101951573260004474105Ozone
20092402063310004158101Ozone
20082121892300003851100Ozone
200722315061120004587129Ozone
20062161823220003958112Ozone
20052151416770004484119Ozone
20042071703520004064112Ozone
20032141654720004267143Ozone
2002213153382020044101174Ozone
20012131475970004487129Ozone
20002291754770004271147Ozone
1999235148621960045101174Ozone
199823415270111004787151Ozone
199723717153112004280159Ozone
199622516446132004287192Ozone
1995225134681850046101169Ozone
1994225144522720045105151Ozone
19932321883950004167126Ozone
19922031484591004480154Ozone
1991207128591820045100174Ozone
1990202139451800044100147Ozone
1989212118722020048101164Ozone
19882221016535201058150203Ozone
1987220126662620046112179Ozone
198627519064192004397195Ozone
198535826773144003687169Ozone
1984328236553430033101197Ozone
1983336251522940035100169Ozone
198228321953110003584140Ozone
1981575610000254071Ozone

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 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