EnviroNearby

Marion County, Indiana air quality history

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

40%
Good days in 2025
54
Median daily AQI, 2025
5
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 Marion, Indiana on 365 days. 146 of those days (40%) were in the Good range, and the median daily AQI was 54. 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 288 days. Across the years with fuller monitoring, the share of Good days rose: an average of 30% in 1980–1982 versus 33% 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 85 of 366 days1980: Moderate 186 of 366 days1980: Unhealthy for Sensitive Groups 63 of 366 days1980: Unhealthy 26 of 366 days1980: Very Unhealthy 6 of 366 days19801981: Good 125 of 365 days1981: Moderate 172 of 365 days1981: Unhealthy for Sensitive Groups 40 of 365 days1981: Unhealthy 24 of 365 days1981: Very Unhealthy 4 of 365 days1982: Good 117 of 365 days1982: Moderate 182 of 365 days1982: Unhealthy for Sensitive Groups 44 of 365 days1982: Unhealthy 19 of 365 days1982: Very Unhealthy 3 of 365 days1983: Good 129 of 365 days1983: Moderate 155 of 365 days1983: Unhealthy for Sensitive Groups 47 of 365 days1983: Unhealthy 29 of 365 days1983: Very Unhealthy 5 of 365 days1984: Good 121 of 366 days1984: Moderate 194 of 366 days1984: Unhealthy for Sensitive Groups 37 of 366 days1984: Unhealthy 13 of 366 days1984: Very Unhealthy 1 of 366 days1985: Good 144 of 365 days1985: Moderate 168 of 365 days1985: Unhealthy for Sensitive Groups 43 of 365 days1985: Unhealthy 7 of 365 days1985: Very Unhealthy 3 of 365 days19851986: Good 144 of 365 days1986: Moderate 174 of 365 days1986: Unhealthy for Sensitive Groups 36 of 365 days1986: Unhealthy 11 of 365 days1987: Good 161 of 365 days1987: Moderate 126 of 365 days1987: Unhealthy for Sensitive Groups 62 of 365 days1987: Unhealthy 14 of 365 days1987: Very Unhealthy 2 of 365 days1988: Good 187 of 366 days1988: Moderate 115 of 366 days1988: Unhealthy for Sensitive Groups 27 of 366 days1988: Unhealthy 31 of 366 days1988: Very Unhealthy 6 of 366 days1989: Good 217 of 365 days1989: Moderate 109 of 365 days1989: Unhealthy for Sensitive Groups 28 of 365 days1989: Unhealthy 11 of 365 days1990: Good 252 of 365 days1990: Moderate 75 of 365 days1990: Unhealthy for Sensitive Groups 32 of 365 days1990: Unhealthy 5 of 365 days1990: Very Unhealthy 1 of 365 days19901991: Good 242 of 365 days1991: Moderate 83 of 365 days1991: Unhealthy for Sensitive Groups 29 of 365 days1991: Unhealthy 11 of 365 days1992: Good 271 of 366 days1992: Moderate 79 of 366 days1992: Unhealthy for Sensitive Groups 10 of 366 days1992: Unhealthy 5 of 366 days1992: Very Unhealthy 1 of 366 days1993: Good 255 of 365 days1993: Moderate 86 of 365 days1993: Unhealthy for Sensitive Groups 20 of 365 days1993: Unhealthy 4 of 365 days1994: Good 238 of 365 days1994: Moderate 72 of 365 days1994: Unhealthy for Sensitive Groups 37 of 365 days1994: Unhealthy 18 of 365 days1995: Good 226 of 365 days1995: Moderate 89 of 365 days1995: Unhealthy for Sensitive Groups 35 of 365 days1995: Unhealthy 14 of 365 days1995: Very Unhealthy 1 of 365 days19951996: Good 258 of 366 days1996: Moderate 69 of 366 days1996: Unhealthy for Sensitive Groups 29 of 366 days1996: Unhealthy 9 of 366 days1996: Very Unhealthy 1 of 366 days1997: Good 275 of 365 days1997: Moderate 62 of 365 days1997: Unhealthy for Sensitive Groups 17 of 365 days1997: Unhealthy 11 of 365 days1998: Good 231 of 365 days1998: Moderate 89 of 365 days1998: Unhealthy for Sensitive Groups 32 of 365 days1998: Unhealthy 13 of 365 days1999: Good 60 of 365 days1999: Moderate 248 of 365 days1999: Unhealthy for Sensitive Groups 44 of 365 days1999: Unhealthy 13 of 365 days2000: Good 46 of 366 days2000: Moderate 291 of 366 days2000: Unhealthy for Sensitive Groups 26 of 366 days2000: Unhealthy 3 of 366 days20002001: Good 49 of 365 days2001: Moderate 270 of 365 days2001: Unhealthy for Sensitive Groups 40 of 365 days2001: Unhealthy 6 of 365 days2002: Good 29 of 365 days2002: Moderate 288 of 365 days2002: Unhealthy for Sensitive Groups 30 of 365 days2002: Unhealthy 14 of 365 days2002: Very Unhealthy 4 of 365 days2003: Good 40 of 365 days2003: Moderate 296 of 365 days2003: Unhealthy for Sensitive Groups 24 of 365 days2003: Unhealthy 5 of 365 days2004: Good 67 of 366 days2004: Moderate 285 of 366 days2004: Unhealthy for Sensitive Groups 14 of 366 days2005: Good 50 of 365 days2005: Moderate 275 of 365 days2005: Unhealthy for Sensitive Groups 36 of 365 days2005: Unhealthy 4 of 365 days20052006: Good 49 of 365 days2006: Moderate 298 of 365 days2006: Unhealthy for Sensitive Groups 18 of 365 days2007: Good 43 of 365 days2007: Moderate 281 of 365 days2007: Unhealthy for Sensitive Groups 40 of 365 days2007: Unhealthy 1 of 365 days2008: Good 66 of 366 days2008: Moderate 293 of 366 days2008: Unhealthy for Sensitive Groups 7 of 366 days2009: Good 59 of 365 days2009: Moderate 299 of 365 days2009: Unhealthy for Sensitive Groups 7 of 365 days2010: Good 53 of 365 days2010: Moderate 299 of 365 days2010: Unhealthy for Sensitive Groups 13 of 365 days20102011: Good 20 of 365 days2011: Moderate 323 of 365 days2011: Unhealthy for Sensitive Groups 22 of 365 days2012: Good 37 of 366 days2012: Moderate 308 of 366 days2012: Unhealthy for Sensitive Groups 19 of 366 days2012: Unhealthy 2 of 366 days2013: Good 59 of 365 days2013: Moderate 300 of 365 days2013: Unhealthy for Sensitive Groups 6 of 365 days2014: Good 85 of 365 days2014: Moderate 273 of 365 days2014: Unhealthy for Sensitive Groups 6 of 365 days2014: Very Unhealthy 1 of 365 days2015: Good 129 of 365 days2015: Moderate 233 of 365 days2015: Unhealthy for Sensitive Groups 2 of 365 days2015: Unhealthy 1 of 365 days20152016: Good 111 of 366 days2016: Moderate 244 of 366 days2016: Unhealthy for Sensitive Groups 11 of 366 days2017: Good 134 of 365 days2017: Moderate 227 of 365 days2017: Unhealthy for Sensitive Groups 4 of 365 days2018: Good 105 of 365 days2018: Moderate 249 of 365 days2018: Unhealthy for Sensitive Groups 10 of 365 days2018: Unhealthy 1 of 365 days2019: Good 78 of 365 days2019: Moderate 283 of 365 days2019: Unhealthy for Sensitive Groups 4 of 365 days2020: Good 110 of 366 days2020: Moderate 250 of 366 days2020: Unhealthy for Sensitive Groups 6 of 366 days20202021: Good 81 of 365 days2021: Moderate 278 of 365 days2021: Unhealthy for Sensitive Groups 6 of 365 days2022: Good 101 of 365 days2022: Moderate 251 of 365 days2022: Unhealthy for Sensitive Groups 12 of 365 days2022: Unhealthy 1 of 365 days2023: Good 84 of 365 days2023: Moderate 260 of 365 days2023: Unhealthy for Sensitive Groups 17 of 365 days2023: Unhealthy 3 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 134 of 366 days2024: Moderate 228 of 366 days2024: Unhealthy for Sensitive Groups 4 of 366 days2025: Good 146 of 365 days2025: Moderate 214 of 365 days2025: Unhealthy for Sensitive Groups 3 of 365 days2025: Unhealthy 2 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 1431981: 90th percentile AQI 1401982: 90th percentile AQI 1261983: 90th percentile AQI 1471984: 90th percentile AQI 1151985: 90th percentile AQI 1151986: 90th percentile AQI 1081987: 90th percentile AQI 1261988: 90th percentile AQI 1511989: 90th percentile AQI 1011990: 90th percentile AQI 1011991: 90th percentile AQI 1081992: 90th percentile AQI 771993: 90th percentile AQI 921994: 90th percentile AQI 1221995: 90th percentile AQI 1151996: 90th percentile AQI 1011997: 90th percentile AQI 931998: 90th percentile AQI 1081999: 90th percentile AQI 1172000: 90th percentile AQI 972001: 90th percentile AQI 1052002: 90th percentile AQI 1122003: 90th percentile AQI 962004: 90th percentile AQI 872005: 90th percentile AQI 1052006: 90th percentile AQI 932007: 90th percentile AQI 1052008: 90th percentile AQI 842009: 90th percentile AQI 822010: 90th percentile AQI 912011: 90th percentile AQI 912012: 90th percentile AQI 902013: 90th percentile AQI 802014: 90th percentile AQI 792015: 90th percentile AQI 742016: 90th percentile AQI 772017: 90th percentile AQI 712018: 90th percentile AQI 732019: 90th percentile AQI 742020: 90th percentile AQI 722021: 90th percentile AQI 812022: 90th percentile AQI 802023: 90th percentile AQI 892024: 90th percentile AQI 742025: 90th percentile AQI 711980: Median AQI 731981: Median AQI 631982: Median AQI 631983: Median AQI 611984: Median AQI 581985: Median AQI 581986: Median AQI 551987: Median AQI 541988: Median AQI 501989: Median AQI 461990: Median AQI 421991: Median AQI 421992: Median AQI 401993: Median AQI 411994: Median AQI 421995: Median AQI 441996: Median AQI 411997: Median AQI 371998: Median AQI 421999: Median AQI 652000: Median AQI 672001: Median AQI 692002: Median AQI 682003: Median AQI 632004: Median AQI 632005: Median AQI 672006: Median AQI 632007: Median AQI 662008: Median AQI 612009: Median AQI 612010: Median AQI 642011: Median AQI 642012: Median AQI 642013: Median AQI 612014: Median AQI 582015: Median AQI 562016: Median AQI 552017: Median AQI 542018: Median AQI 552019: Median AQI 582020: Median AQI 552021: Median AQI 582022: Median AQI 562023: Median AQI 602024: Median AQI 542025: Median AQI 541980198519901995200020052010201520202025
  • 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)28879%
Ozone7521%
Coarse particles (PM10)21%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536514621432005471170PM2.5
202436613422840005474138PM2.5
202336584260173106089259PM2.5
2022365101251121005680154PM2.5
20213658127860005881114PM2.5
202036611025060005572144PM2.5
20193657828340005874112PM2.5
2018365105249101005573158PM2.5
201736513422740005471122PM2.5
2016366111244110005577143PM2.5
201536512923321005674159PM2.5
20143658527360105879209PM2.5
20133655930060006180124PM2.5
201236637308192006490169PM2.5
201136520323220006491141PM2.5
201036553299130006491143PM2.5
20093655929970006182133PM2.5
20083666629370006184143PM2.5
2007365432814010066105174PM2.5
200636549298180006393140PM2.5
2005365502753640067105159PM2.5
200436667285140006387125PM2.5
200336540296245006396197PM2.5
20023652928830144068112227PM2.5
2001365492704060069105182PM2.5
200036646291263006797182PM2.5
19993656024844130065117190PM2.5
19983652318932130042108192Ozone
1997365275621711003793200Ozone
1996366258692991041101221Ozone
19953652268935141044115201Ozone
19943652387237180042122197Ozone
199336525586204004192169Ozone
199236627179105104077214Ozone
19913652428329110042108185Ozone
1990365252753251042101207Ozone
198936521710928110046101197NO2
198836618711527316050151223NO2
198736516112662142054126202Ozone
198636514417436110055108185Ozone
19853651441684373058115213Ozone
198436612119437131058115210CO
198336512915547295061147213Ozone
198236511718244193063126214CO
198136512517240244063140226CO
19803668518663266073143210CO

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