EnviroNearby

La Salle County, Illinois air quality history

Daily Air Quality Index summaries from EPA monitors in La Salle, Illinois, 1980–2010.

64%
Good days in 2010
42
Median daily AQI, 2010
0
Days above 100 in 2010
365
Days with an AQI in 2010 (of 365)

In 2010, EPA reported a daily Air Quality Index (AQI) for La Salle, Illinois on 365 days. 232 of those days (64%) were in the Good range, and the median daily AQI was 42. That median is about the same as the typical monitored county in Illinois (median 40 across 24 counties), and about the same as the typical monitored U.S. county (44). The main pollutant was fine particles (PM2.5) on 283 days. Across the years with fuller monitoring, the share of Good days fell: an average of 89% in 1980–1982 versus 53% in 2008–2010.

The most recent year with data for this county is 2010; EPA's files for 2011–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1989, 1990, 1991, 1992, 1993, 1994…) 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%1980: Good 240 of 282 days1980: Moderate 27 of 282 days1980: Unhealthy for Sensitive Groups 13 of 282 days1980: Unhealthy 2 of 282 days19801981: Good 260 of 306 days1981: Moderate 37 of 306 days1981: Unhealthy for Sensitive Groups 6 of 306 days1981: Unhealthy 3 of 306 days1982: Good 266 of 275 days1982: Moderate 8 of 275 days1982: Unhealthy for Sensitive Groups 1 of 275 days1983: Good 143 of 187 days1983: Moderate 36 of 187 days1983: Unhealthy for Sensitive Groups 8 of 187 days1986: Good 42 of 55 days1986: Moderate 13 of 55 days1987: Good 34 of 56 days1987: Moderate 19 of 56 days1987: Unhealthy for Sensitive Groups 3 of 56 days19871988: Good 38 of 59 days1988: Moderate 21 of 59 days1989: Good 38 of 60 days1989: Moderate 18 of 60 days1989: Unhealthy for Sensitive Groups 1 of 60 days1989: Unhealthy 3 of 60 days1990: Good 38 of 58 days1990: Moderate 17 of 58 days1990: Unhealthy for Sensitive Groups 3 of 58 days1991: Good 46 of 57 days1991: Moderate 8 of 57 days1991: Unhealthy for Sensitive Groups 3 of 57 days1992: Good 39 of 50 days1992: Moderate 11 of 50 days19921993: Good 52 of 56 days1993: Moderate 4 of 56 days1994: Good 49 of 59 days1994: Moderate 10 of 59 days1995: Good 314 of 360 days1995: Moderate 46 of 360 days1996: Good 333 of 366 days1996: Moderate 33 of 366 days1997: Good 334 of 364 days1997: Moderate 30 of 364 days19971998: Good 331 of 363 days1998: Moderate 31 of 363 days1998: Unhealthy for Sensitive Groups 1 of 363 days1999: Good 327 of 363 days1999: Moderate 36 of 363 days2000: Good 266 of 363 days2000: Moderate 95 of 363 days2000: Unhealthy for Sensitive Groups 2 of 363 days2001: Good 256 of 358 days2001: Moderate 101 of 358 days2001: Unhealthy for Sensitive Groups 1 of 358 days2002: Good 252 of 358 days2002: Moderate 105 of 358 days2002: Unhealthy for Sensitive Groups 1 of 358 days20022003: Good 272 of 365 days2003: Moderate 92 of 365 days2003: Unhealthy for Sensitive Groups 1 of 365 days2004: Good 285 of 364 days2004: Moderate 78 of 364 days2004: Unhealthy for Sensitive Groups 1 of 364 days2005: Good 275 of 365 days2005: Moderate 88 of 365 days2005: Unhealthy for Sensitive Groups 2 of 365 days2006: Good 290 of 362 days2006: Moderate 72 of 362 days2007: Good 122 of 365 days2007: Moderate 241 of 365 days2007: Unhealthy for Sensitive Groups 2 of 365 days20072008: Good 173 of 366 days2008: Moderate 193 of 366 days2009: Good 180 of 365 days2009: Moderate 185 of 365 days2010: Good 232 of 365 days2010: Moderate 133 of 365 days2010
  • 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 year0501001980: 90th percentile AQI 711981: 90th percentile AQI 671982: 90th percentile AQI 461983: 90th percentile AQI 841986: 90th percentile AQI 761987: 90th percentile AQI 871988: 90th percentile AQI 831989: 90th percentile AQI 881990: 90th percentile AQI 781991: 90th percentile AQI 661992: 90th percentile AQI 591993: 90th percentile AQI 391994: 90th percentile AQI 601995: 90th percentile AQI 531996: 90th percentile AQI 491997: 90th percentile AQI 441998: 90th percentile AQI 491999: 90th percentile AQI 502000: 90th percentile AQI 672001: 90th percentile AQI 672002: 90th percentile AQI 672003: 90th percentile AQI 612004: 90th percentile AQI 592005: 90th percentile AQI 612006: 90th percentile AQI 592007: 90th percentile AQI 712008: 90th percentile AQI 662009: 90th percentile AQI 662010: 90th percentile AQI 631980: Median AQI 291981: Median AQI 311982: Median AQI 311983: Median AQI 381986: Median AQI 331987: Median AQI 321988: Median AQI 391989: Median AQI 421990: Median AQI 361991: Median AQI 281992: Median AQI 281993: Median AQI 211994: Median AQI 271995: Median AQI 231996: Median AQI 221997: Median AQI 201998: Median AQI 221999: Median AQI 212000: Median AQI 272001: Median AQI 252002: Median AQI 292003: Median AQI 252004: Median AQI 282005: Median AQI 302006: Median AQI 262007: Median AQI 552008: Median AQI 512009: Median AQI 512010: Median AQI 421980198719921997200220072010
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2010

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)28378%
Coarse particles (PM10)8222%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20103652321330000426394PM2.5
20093651801850000516687PM2.5
20083661731930000516691PM2.5
200736512224120005571114PM2.5
2006362290720000265989PM10
20053652758820003061130PM10
20043642857810002859104PM10
20033652729210002561103PM10
200235825210510002967110PM10
200135825610110002567115PM10
20003632669520002767109PM10
1999363327360000215098PM10
19983633313110002249104PM10
1997364334300000204497PM10
1996366333330000224993PM10
1995360314460000235381PM10
19945949100000276077PM10
1993565240000213984PM10
19925039110000285992PM10
19915746830002866120PM10
199058381730003678124PM10
198960381813004288179PM10
198859382100003983100PM10
198756341930003287128PM10
19865542130000337698PM10
19831871433680003884147Ozone
1982275266810003146108Ozone
19813062603763003167169Ozone
198028224027132002971161Ozone

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.

All monitored counties in Illinois

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2010 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem