EnviroNearby

Lake County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in Lake, Indiana, 1980–2025.

42%
Good days in 2025
53
Median daily AQI, 2025
15
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 Lake, Indiana on 365 days. 152 of those days (42%) were in the Good range, and the median daily AQI was 53. That median is higher than the typical monitored county in Indiana (median 41 across 33 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 279 days. Across the years with fuller monitoring, the share of Good days fell: an average of 78% in 1980–1982 versus 40% 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 284 of 339 days1980: Moderate 22 of 339 days1980: Unhealthy for Sensitive Groups 23 of 339 days1980: Unhealthy 9 of 339 days1980: Very Unhealthy 1 of 339 days19801981: Good 277 of 365 days1981: Moderate 57 of 365 days1981: Unhealthy for Sensitive Groups 26 of 365 days1981: Unhealthy 3 of 365 days1981: Very Unhealthy 2 of 365 days1982: Good 273 of 365 days1982: Moderate 57 of 365 days1982: Unhealthy for Sensitive Groups 25 of 365 days1982: Unhealthy 7 of 365 days1982: Very Unhealthy 3 of 365 days1983: Good 269 of 365 days1983: Moderate 49 of 365 days1983: Unhealthy for Sensitive Groups 29 of 365 days1983: Unhealthy 15 of 365 days1983: Very Unhealthy 3 of 365 days1984: Good 277 of 366 days1984: Moderate 53 of 366 days1984: Unhealthy for Sensitive Groups 22 of 366 days1984: Unhealthy 11 of 366 days1984: Very Unhealthy 3 of 366 days1985: Good 211 of 365 days1985: Moderate 136 of 365 days1985: Unhealthy for Sensitive Groups 14 of 365 days1985: Unhealthy 4 of 365 days19851986: Good 239 of 365 days1986: Moderate 110 of 365 days1986: Unhealthy for Sensitive Groups 14 of 365 days1986: Unhealthy 2 of 365 days1987: Good 227 of 365 days1987: Moderate 106 of 365 days1987: Unhealthy for Sensitive Groups 25 of 365 days1987: Unhealthy 6 of 365 days1987: Very Unhealthy 1 of 365 days1988: Good 200 of 366 days1988: Moderate 107 of 366 days1988: Unhealthy for Sensitive Groups 38 of 366 days1988: Unhealthy 16 of 366 days1988: Very Unhealthy 5 of 366 days1989: Good 168 of 364 days1989: Moderate 146 of 364 days1989: Unhealthy for Sensitive Groups 38 of 364 days1989: Unhealthy 11 of 364 days1989: Very Unhealthy 1 of 364 days1990: Good 221 of 365 days1990: Moderate 125 of 365 days1990: Unhealthy for Sensitive Groups 18 of 365 days1990: Unhealthy 1 of 365 days19901991: Good 222 of 365 days1991: Moderate 106 of 365 days1991: Unhealthy for Sensitive Groups 29 of 365 days1991: Unhealthy 8 of 365 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 280 of 365 days1993: Moderate 77 of 365 days1993: Unhealthy for Sensitive Groups 8 of 365 days1994: Good 239 of 365 days1994: Moderate 105 of 365 days1994: Unhealthy for Sensitive Groups 15 of 365 days1994: Unhealthy 6 of 365 days1995: Good 220 of 365 days1995: Moderate 107 of 365 days1995: Unhealthy for Sensitive Groups 24 of 365 days1995: Unhealthy 11 of 365 days1995: Very Unhealthy 3 of 365 days19951996: Good 238 of 366 days1996: Moderate 104 of 366 days1996: Unhealthy for Sensitive Groups 17 of 366 days1996: Unhealthy 6 of 366 days1996: Very Unhealthy 1 of 366 days1997: Good 248 of 365 days1997: Moderate 91 of 365 days1997: Unhealthy for Sensitive Groups 16 of 365 days1997: Unhealthy 10 of 365 days1998: Good 231 of 365 days1998: Moderate 98 of 365 days1998: Unhealthy for Sensitive Groups 28 of 365 days1998: Unhealthy 7 of 365 days1998: Very Unhealthy 1 of 365 days1999: Good 37 of 365 days1999: Moderate 270 of 365 days1999: Unhealthy for Sensitive Groups 45 of 365 days1999: Unhealthy 13 of 365 days2000: Good 39 of 366 days2000: Moderate 293 of 366 days2000: Unhealthy for Sensitive Groups 26 of 366 days2000: Unhealthy 8 of 366 days20002001: Good 38 of 365 days2001: Moderate 262 of 365 days2001: Unhealthy for Sensitive Groups 52 of 365 days2001: Unhealthy 13 of 365 days2002: Good 44 of 365 days2002: Moderate 278 of 365 days2002: Unhealthy for Sensitive Groups 24 of 365 days2002: Unhealthy 18 of 365 days2002: Very Unhealthy 1 of 365 days2003: Good 58 of 365 days2003: Moderate 268 of 365 days2003: Unhealthy for Sensitive Groups 34 of 365 days2003: Unhealthy 5 of 365 days2004: Good 68 of 366 days2004: Moderate 279 of 366 days2004: Unhealthy for Sensitive Groups 17 of 366 days2004: Unhealthy 2 of 366 days2005: Good 44 of 365 days2005: Moderate 276 of 365 days2005: Unhealthy for Sensitive Groups 36 of 365 days2005: Unhealthy 9 of 365 days20052006: Good 72 of 365 days2006: Moderate 281 of 365 days2006: Unhealthy for Sensitive Groups 11 of 365 days2006: Unhealthy 1 of 365 days2007: Good 66 of 365 days2007: Moderate 272 of 365 days2007: Unhealthy for Sensitive Groups 22 of 365 days2007: Unhealthy 5 of 365 days2008: Good 76 of 366 days2008: Moderate 285 of 366 days2008: Unhealthy for Sensitive Groups 5 of 366 days2009: Good 95 of 365 days2009: Moderate 267 of 365 days2009: Unhealthy for Sensitive Groups 3 of 365 days2010: Good 54 of 365 days2010: Moderate 294 of 365 days2010: Unhealthy for Sensitive Groups 17 of 365 days20102011: Good 81 of 365 days2011: Moderate 275 of 365 days2011: Unhealthy for Sensitive Groups 7 of 365 days2011: Unhealthy 2 of 365 days2012: Good 75 of 366 days2012: Moderate 270 of 366 days2012: Unhealthy for Sensitive Groups 18 of 366 days2012: Unhealthy 3 of 366 days2013: Good 88 of 365 days2013: Moderate 276 of 365 days2013: Unhealthy for Sensitive Groups 1 of 365 days2014: Good 66 of 365 days2014: Moderate 291 of 365 days2014: Unhealthy for Sensitive Groups 7 of 365 days2014: Unhealthy 1 of 365 days2015: Good 141 of 365 days2015: Moderate 218 of 365 days2015: Unhealthy for Sensitive Groups 5 of 365 days2015: Unhealthy 1 of 365 days20152016: Good 183 of 366 days2016: Moderate 177 of 366 days2016: Unhealthy for Sensitive Groups 5 of 366 days2016: Very Unhealthy 1 of 366 days2017: Good 203 of 365 days2017: Moderate 157 of 365 days2017: Unhealthy for Sensitive Groups 4 of 365 days2017: Unhealthy 1 of 365 days2018: Good 139 of 365 days2018: Moderate 220 of 365 days2018: Unhealthy for Sensitive Groups 5 of 365 days2018: Unhealthy 1 of 365 days2019: Good 151 of 365 days2019: Moderate 213 of 365 days2019: Unhealthy for Sensitive Groups 1 of 365 days2020: Good 161 of 366 days2020: Moderate 199 of 366 days2020: Unhealthy for Sensitive Groups 6 of 366 days20202021: Good 134 of 365 days2021: Moderate 225 of 365 days2021: Unhealthy for Sensitive Groups 5 of 365 days2021: Unhealthy 1 of 365 days2022: Good 152 of 365 days2022: Moderate 208 of 365 days2022: Unhealthy for Sensitive Groups 5 of 365 days2023: Good 125 of 365 days2023: Moderate 222 of 365 days2023: Unhealthy for Sensitive Groups 16 of 365 days2023: Unhealthy 1 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 162 of 366 days2024: Moderate 199 of 366 days2024: Unhealthy for Sensitive Groups 4 of 366 days2024: Unhealthy 1 of 366 days2025: Good 152 of 365 days2025: Moderate 198 of 365 days2025: Unhealthy for Sensitive Groups 11 of 365 days2025: Unhealthy 3 of 365 days2025: Very Unhealthy 1 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 1001981: 90th percentile AQI 931982: 90th percentile AQI 1001983: 90th percentile AQI 1191984: 90th percentile AQI 971985: 90th percentile AQI 841986: 90th percentile AQI 791987: 90th percentile AQI 971988: 90th percentile AQI 1261989: 90th percentile AQI 1081990: 90th percentile AQI 801991: 90th percentile AQI 1011992: 90th percentile AQI 691993: 90th percentile AQI 641994: 90th percentile AQI 771995: 90th percentile AQI 1011996: 90th percentile AQI 841997: 90th percentile AQI 871998: 90th percentile AQI 1001999: 90th percentile AQI 1182000: 90th percentile AQI 982001: 90th percentile AQI 1222002: 90th percentile AQI 1082003: 90th percentile AQI 1012004: 90th percentile AQI 872005: 90th percentile AQI 1082006: 90th percentile AQI 842007: 90th percentile AQI 902008: 90th percentile AQI 772009: 90th percentile AQI 772010: 90th percentile AQI 902011: 90th percentile AQI 822012: 90th percentile AQI 902013: 90th percentile AQI 752014: 90th percentile AQI 802015: 90th percentile AQI 742016: 90th percentile AQI 672017: 90th percentile AQI 662018: 90th percentile AQI 692019: 90th percentile AQI 722020: 90th percentile AQI 682021: 90th percentile AQI 722022: 90th percentile AQI 692023: 90th percentile AQI 802024: 90th percentile AQI 712025: 90th percentile AQI 751980: Median AQI 221981: Median AQI 351982: Median AQI 361983: Median AQI 341984: Median AQI 341985: Median AQI 441986: Median AQI 411987: Median AQI 421988: Median AQI 461989: Median AQI 531990: Median AQI 451991: Median AQI 441992: Median AQI 401993: Median AQI 391994: Median AQI 441995: Median AQI 441996: Median AQI 431997: Median AQI 421998: Median AQI 431999: Median AQI 682000: Median AQI 692001: Median AQI 702002: Median AQI 662003: Median AQI 632004: Median AQI 612005: Median AQI 642006: Median AQI 602007: Median AQI 592008: Median AQI 572009: Median AQI 572010: Median AQI 672011: Median AQI 592012: Median AQI 582013: Median AQI 582014: Median AQI 612015: Median AQI 542016: Median AQI 512017: Median AQI 492018: Median AQI 542019: Median AQI 522020: Median AQI 522021: Median AQI 542022: Median AQI 522023: Median AQI 552024: Median AQI 522025: Median AQI 531980198519901995200020052010201520202025
  • 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)27976%
Ozone8022%
Coarse particles (PM10)51%
Nitrogen dioxide (NO₂)1<1%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365152198113105375219PM2.5
202436616219941005271166PM2.5
2023365125222161105580215PM2.5
202236515220850005269143PM2.5
202136513422551005472175PM2.5
202036616119960005268136PM2.5
201936515121310005272101PM2.5
201836513922051005469151PM2.5
201736520315741004966173PM2.5
201636618317750105167242PM2.5
201536514121851005474151PM2.5
20143656629171006180156PM2.5
20133658827610005875114PM2.5
201236675270183005890179PM2.5
20113658127572005982158PM2.5
201036554294170006790133PM2.5
20093659526730005777119PM2.5
20083667628550005777122PM2.5
200736566272225005990172PM2.5
200636572281111006084151PM2.5
2005365442763690064108198PM2.5
200436668279172006187153PM2.5
2003365582683450063101190PM2.5
20023654427824181066108206PM2.5
20013653826252130070122179PM2.5
200036639293268006998164PM2.5
19993653727045130068118192PM2.5
1998365231982871043100201Ozone
1997365248911610004287187Ozone
1996366238104176104384204NO2
199536522010724113044101225NO2
1994365239105156004477190NO2
19933652807780003964126NO2
19923662609592004069195NO2
19913652221062980044101179PM10
1990365221125181004580166NO2
198936416814638111053108203Ozone
198836620010738165046126227PM10
1987365227106256104297206PM10
1986365239110142004179166PM10
1985365211136144004484200PM10
1984366277532211303497208Ozone
19833652694929153034119233Ozone
1982365273572573036100209Ozone
198136527757263203593236Ozone
1980339284222391022100214Ozone

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 Indiana with a similar median AQI in 2025

All monitored counties in Indiana

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