EnviroNearby

Clark County, Indiana air quality history

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

58%
Good days in 2025
46
Median daily AQI, 2025
3
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 Clark, Indiana on 365 days. 212 of those days (58%) were in the Good range, and the median daily AQI was 46. 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 240 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 51% in 1980–1982 versus 52% 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 69 of 204 days1980: Moderate 39 of 204 days1980: Unhealthy for Sensitive Groups 57 of 204 days1980: Unhealthy 26 of 204 days1980: Very Unhealthy 13 of 204 days19801981: Good 190 of 351 days1981: Moderate 119 of 351 days1981: Unhealthy for Sensitive Groups 27 of 351 days1981: Unhealthy 12 of 351 days1981: Very Unhealthy 3 of 351 days1982: Good 214 of 332 days1982: Moderate 77 of 332 days1982: Unhealthy for Sensitive Groups 25 of 332 days1982: Unhealthy 12 of 332 days1982: Very Unhealthy 4 of 332 days1983: Good 225 of 301 days1983: Moderate 35 of 301 days1983: Unhealthy for Sensitive Groups 22 of 301 days1983: Unhealthy 16 of 301 days1983: Very Unhealthy 3 of 301 days1984: Good 256 of 333 days1984: Moderate 52 of 333 days1984: Unhealthy for Sensitive Groups 19 of 333 days1984: Unhealthy 6 of 333 days1985: Good 170 of 273 days1985: Moderate 68 of 273 days1985: Unhealthy for Sensitive Groups 27 of 273 days1985: Unhealthy 6 of 273 days1985: Very Unhealthy 2 of 273 days19851986: Good 86 of 235 days1986: Moderate 69 of 235 days1986: Unhealthy for Sensitive Groups 49 of 235 days1986: Unhealthy 26 of 235 days1986: Very Unhealthy 5 of 235 days1987: Good 109 of 193 days1987: Moderate 48 of 193 days1987: Unhealthy for Sensitive Groups 27 of 193 days1987: Unhealthy 9 of 193 days1988: Good 120 of 231 days1988: Moderate 49 of 231 days1988: Unhealthy for Sensitive Groups 28 of 231 days1988: Unhealthy 26 of 231 days1988: Very Unhealthy 8 of 231 days1989: Good 112 of 231 days1989: Moderate 81 of 231 days1989: Unhealthy for Sensitive Groups 30 of 231 days1989: Unhealthy 7 of 231 days1989: Very Unhealthy 1 of 231 days1990: Good 145 of 227 days1990: Moderate 48 of 227 days1990: Unhealthy for Sensitive Groups 26 of 227 days1990: Unhealthy 7 of 227 days1990: Very Unhealthy 1 of 227 days19901991: Good 104 of 193 days1991: Moderate 49 of 193 days1991: Unhealthy for Sensitive Groups 29 of 193 days1991: Unhealthy 8 of 193 days1991: Very Unhealthy 3 of 193 days1992: Good 129 of 208 days1992: Moderate 65 of 208 days1992: Unhealthy for Sensitive Groups 12 of 208 days1992: Unhealthy 2 of 208 days1993: Good 120 of 204 days1993: Moderate 49 of 204 days1993: Unhealthy for Sensitive Groups 18 of 204 days1993: Unhealthy 16 of 204 days1993: Very Unhealthy 1 of 204 days1994: Good 125 of 239 days1994: Moderate 53 of 239 days1994: Unhealthy for Sensitive Groups 39 of 239 days1994: Unhealthy 19 of 239 days1994: Very Unhealthy 3 of 239 days1995: Good 105 of 207 days1995: Moderate 56 of 207 days1995: Unhealthy for Sensitive Groups 29 of 207 days1995: Unhealthy 14 of 207 days1995: Very Unhealthy 3 of 207 days19951996: Good 145 of 207 days1996: Moderate 46 of 207 days1996: Unhealthy for Sensitive Groups 14 of 207 days1996: Unhealthy 2 of 207 days1997: Good 135 of 222 days1997: Moderate 51 of 222 days1997: Unhealthy for Sensitive Groups 26 of 222 days1997: Unhealthy 9 of 222 days1997: Very Unhealthy 1 of 222 days1998: Good 102 of 220 days1998: Moderate 67 of 220 days1998: Unhealthy for Sensitive Groups 31 of 220 days1998: Unhealthy 17 of 220 days1998: Very Unhealthy 3 of 220 days1999: Good 96 of 257 days1999: Moderate 121 of 257 days1999: Unhealthy for Sensitive Groups 31 of 257 days1999: Unhealthy 9 of 257 days2000: Good 105 of 254 days2000: Moderate 118 of 254 days2000: Unhealthy for Sensitive Groups 27 of 254 days2000: Unhealthy 4 of 254 days20002001: Good 106 of 263 days2001: Moderate 128 of 263 days2001: Unhealthy for Sensitive Groups 24 of 263 days2001: Unhealthy 5 of 263 days2002: Good 93 of 261 days2002: Moderate 127 of 261 days2002: Unhealthy for Sensitive Groups 27 of 261 days2002: Unhealthy 14 of 261 days2003: Good 151 of 296 days2003: Moderate 126 of 296 days2003: Unhealthy for Sensitive Groups 15 of 296 days2003: Unhealthy 4 of 296 days2004: Good 186 of 322 days2004: Moderate 130 of 322 days2004: Unhealthy for Sensitive Groups 6 of 322 days2005: Good 101 of 259 days2005: Moderate 126 of 259 days2005: Unhealthy for Sensitive Groups 29 of 259 days2005: Unhealthy 3 of 259 days20052006: Good 107 of 245 days2006: Moderate 128 of 245 days2006: Unhealthy for Sensitive Groups 7 of 245 days2006: Unhealthy 3 of 245 days2007: Good 52 of 354 days2007: Moderate 260 of 354 days2007: Unhealthy for Sensitive Groups 35 of 354 days2007: Unhealthy 7 of 354 days2008: Good 78 of 346 days2008: Moderate 253 of 346 days2008: Unhealthy for Sensitive Groups 15 of 346 days2009: Good 93 of 362 days2009: Moderate 268 of 362 days2009: Unhealthy for Sensitive Groups 1 of 362 days2010: Good 73 of 354 days2010: Moderate 265 of 354 days2010: Unhealthy for Sensitive Groups 16 of 354 days20102011: Good 110 of 342 days2011: Moderate 212 of 342 days2011: Unhealthy for Sensitive Groups 18 of 342 days2011: Unhealthy 2 of 342 days2012: Good 116 of 356 days2012: Moderate 220 of 356 days2012: Unhealthy for Sensitive Groups 17 of 356 days2012: Unhealthy 3 of 356 days2013: Good 130 of 357 days2013: Moderate 227 of 357 days2014: Good 123 of 335 days2014: Moderate 210 of 335 days2014: Unhealthy for Sensitive Groups 2 of 335 days2015: Good 160 of 364 days2015: Moderate 200 of 364 days2015: Unhealthy for Sensitive Groups 3 of 364 days2015: Unhealthy 1 of 364 days20152016: Good 195 of 365 days2016: Moderate 163 of 365 days2016: Unhealthy for Sensitive Groups 7 of 365 days2017: Good 286 of 364 days2017: Moderate 77 of 364 days2017: Unhealthy for Sensitive Groups 1 of 364 days2018: Good 276 of 357 days2018: Moderate 77 of 357 days2018: Unhealthy for Sensitive Groups 4 of 357 days2019: Good 225 of 365 days2019: Moderate 139 of 365 days2019: Unhealthy for Sensitive Groups 1 of 365 days2020: Good 186 of 366 days2020: Moderate 180 of 366 days20202021: Good 160 of 365 days2021: Moderate 205 of 365 days2022: Good 170 of 363 days2022: Moderate 192 of 363 days2022: Unhealthy for Sensitive Groups 1 of 363 days2023: Good 146 of 365 days2023: Moderate 208 of 365 days2023: Unhealthy for Sensitive Groups 10 of 365 days2023: Unhealthy 1 of 365 days2024: Good 216 of 366 days2024: Moderate 146 of 366 days2024: Unhealthy for Sensitive Groups 4 of 366 days2025: Good 212 of 365 days2025: Moderate 150 of 365 days2025: Unhealthy for Sensitive Groups 3 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 year0501001502001980: 90th percentile AQI 1721981: 90th percentile AQI 1051982: 90th percentile AQI 1081983: 90th percentile AQI 1261984: 90th percentile AQI 841985: 90th percentile AQI 1051986: 90th percentile AQI 1591987: 90th percentile AQI 1291988: 90th percentile AQI 1691989: 90th percentile AQI 1221990: 90th percentile AQI 1191991: 90th percentile AQI 1291992: 90th percentile AQI 931993: 90th percentile AQI 1361994: 90th percentile AQI 1501995: 90th percentile AQI 1431996: 90th percentile AQI 931997: 90th percentile AQI 1121998: 90th percentile AQI 1501999: 90th percentile AQI 1192000: 90th percentile AQI 1052001: 90th percentile AQI 1012002: 90th percentile AQI 1332003: 90th percentile AQI 902004: 90th percentile AQI 772005: 90th percentile AQI 1082006: 90th percentile AQI 872007: 90th percentile AQI 1122008: 90th percentile AQI 862009: 90th percentile AQI 762010: 90th percentile AQI 842011: 90th percentile AQI 842012: 90th percentile AQI 842013: 90th percentile AQI 712014: 90th percentile AQI 742015: 90th percentile AQI 702016: 90th percentile AQI 672017: 90th percentile AQI 602018: 90th percentile AQI 612019: 90th percentile AQI 622020: 90th percentile AQI 622021: 90th percentile AQI 712022: 90th percentile AQI 662023: 90th percentile AQI 722024: 90th percentile AQI 632025: 90th percentile AQI 611980: Median AQI 931981: Median AQI 481982: Median AQI 431983: Median AQI 351984: Median AQI 361985: Median AQI 431986: Median AQI 671987: Median AQI 461988: Median AQI 491989: Median AQI 511990: Median AQI 441991: Median AQI 471992: Median AQI 451993: Median AQI 471994: Median AQI 491995: Median AQI 501996: Median AQI 421997: Median AQI 471998: Median AQI 541999: Median AQI 582000: Median AQI 572001: Median AQI 582002: Median AQI 582003: Median AQI 502004: Median AQI 462005: Median AQI 582006: Median AQI 542007: Median AQI 642008: Median AQI 602009: Median AQI 572010: Median AQI 612011: Median AQI 562012: Median AQI 552013: Median AQI 542014: Median AQI 542015: Median AQI 522016: Median AQI 492017: Median AQI 402018: Median AQI 372019: Median AQI 452020: Median AQI 502021: Median AQI 522022: Median AQI 512023: Median AQI 522024: Median AQI 472025: Median AQI 461980198519901995200020052010201520202025
  • 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)24066%
Ozone12534%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536521215030004661133PM2.5
202436621614640004763150PM2.5
2023365146208101005272182PM2.5
202236317019210005166119PM2.5
20213651602050000527196PM2.5
20203661861800000506292PM2.5
201936522513910004562101Ozone
20183572767740003761122Ozone
20173642867710004060101Ozone
201636519516370004967143PM2.5
201536416020031005270164PM2.5
201433512321020005474122PM2.5
20133571302270000547193PM2.5
2012356116220173005584164PM2.5
2011342110212182005684161PM2.5
201035473265160006184147PM2.5
20093629326810005776105PM2.5
200834678253150006086150PM2.5
2007354522603570064112174PM2.5
200624510712873005487166Ozone
20052591011262930058108182Ozone
200432218613060004677133Ozone
2003296151126154005090177Ozone
20022619312727140058133195Ozone
20012631061282450058101177Ozone
20002541051182740057105156Ozone
1999257961213190058119177Ozone
19982201026731173054150228Ozone
1997222135512691047112206Ozone
199620714546142004293172Ozone
19952071055629143050143209Ozone
19942391255339193049150213Ozone
19932041204918161047136209Ozone
199220812965122004593185Ozone
1991193104492983047129229Ozone
1990227145482671044119204Ozone
1989231112813071051122209Ozone
19882311204928268049169227Ozone
1987193109482790046129164Ozone
1986235866949265067159247Ozone
1985273170682762043105232Ozone
198433325652196003684172Ozone
19833012253522163035126219Ozone
19823322147725124043108221Ozone
198135119011927123048105205NO2
19802046939572613093172237Ozone

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