EnviroNearby

Franklin County, Ohio air quality history

Daily Air Quality Index summaries from EPA monitors in Franklin, Ohio, 1980–2025.

40%
Good days in 2025
53
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 Franklin, Ohio on 365 days. 147 of those days (40%) were in the Good range, and the median daily AQI was 53. That median is higher than the typical monitored county in Ohio (median 43 across 36 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 263 days. Across the years with fuller monitoring, the share of Good days fell: an average of 47% 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 151 of 366 days1980: Moderate 143 of 366 days1980: Unhealthy for Sensitive Groups 54 of 366 days1980: Unhealthy 17 of 366 days1980: Very Unhealthy 1 of 366 days19801981: Good 158 of 365 days1981: Moderate 171 of 365 days1981: Unhealthy for Sensitive Groups 29 of 365 days1981: Unhealthy 7 of 365 days1982: Good 207 of 365 days1982: Moderate 122 of 365 days1982: Unhealthy for Sensitive Groups 21 of 365 days1982: Unhealthy 13 of 365 days1982: Very Unhealthy 2 of 365 days1983: Good 201 of 365 days1983: Moderate 114 of 365 days1983: Unhealthy for Sensitive Groups 32 of 365 days1983: Unhealthy 17 of 365 days1983: Very Unhealthy 1 of 365 days1984: Good 215 of 366 days1984: Moderate 127 of 366 days1984: Unhealthy for Sensitive Groups 18 of 366 days1984: Unhealthy 6 of 366 days1985: Good 208 of 365 days1985: Moderate 122 of 365 days1985: Unhealthy for Sensitive Groups 30 of 365 days1985: Unhealthy 5 of 365 days19851986: Good 246 of 365 days1986: Moderate 102 of 365 days1986: Unhealthy for Sensitive Groups 11 of 365 days1986: Unhealthy 6 of 365 days1987: Good 242 of 365 days1987: Moderate 91 of 365 days1987: Unhealthy for Sensitive Groups 23 of 365 days1987: Unhealthy 8 of 365 days1987: Very Unhealthy 1 of 365 days1988: Good 272 of 366 days1988: Moderate 50 of 366 days1988: Unhealthy for Sensitive Groups 22 of 366 days1988: Unhealthy 18 of 366 days1988: Very Unhealthy 4 of 366 days1989: Good 276 of 365 days1989: Moderate 62 of 365 days1989: Unhealthy for Sensitive Groups 20 of 365 days1989: Unhealthy 7 of 365 days1990: Good 286 of 365 days1990: Moderate 55 of 365 days1990: Unhealthy for Sensitive Groups 20 of 365 days1990: Unhealthy 4 of 365 days19901991: Good 257 of 365 days1991: Moderate 73 of 365 days1991: Unhealthy for Sensitive Groups 27 of 365 days1991: Unhealthy 6 of 365 days1991: Very Unhealthy 2 of 365 days1992: Good 303 of 366 days1992: Moderate 51 of 366 days1992: Unhealthy for Sensitive Groups 12 of 366 days1993: Good 279 of 365 days1993: Moderate 57 of 365 days1993: Unhealthy for Sensitive Groups 24 of 365 days1993: Unhealthy 5 of 365 days1994: Good 269 of 365 days1994: Moderate 63 of 365 days1994: Unhealthy for Sensitive Groups 27 of 365 days1994: Unhealthy 6 of 365 days1995: Good 277 of 365 days1995: Moderate 60 of 365 days1995: Unhealthy for Sensitive Groups 22 of 365 days1995: Unhealthy 5 of 365 days1995: Very Unhealthy 1 of 365 days19951996: Good 276 of 366 days1996: Moderate 47 of 366 days1996: Unhealthy for Sensitive Groups 32 of 366 days1996: Unhealthy 10 of 366 days1996: Very Unhealthy 1 of 366 days1997: Good 289 of 365 days1997: Moderate 56 of 365 days1997: Unhealthy for Sensitive Groups 15 of 365 days1997: Unhealthy 5 of 365 days1998: Good 253 of 365 days1998: Moderate 68 of 365 days1998: Unhealthy for Sensitive Groups 29 of 365 days1998: Unhealthy 15 of 365 days1999: Good 45 of 365 days1999: Moderate 260 of 365 days1999: Unhealthy for Sensitive Groups 45 of 365 days1999: Unhealthy 13 of 365 days1999: Very Unhealthy 2 of 365 days2000: Good 60 of 366 days2000: Moderate 279 of 366 days2000: Unhealthy for Sensitive Groups 26 of 366 days2000: Unhealthy 1 of 366 days20002001: Good 58 of 365 days2001: Moderate 263 of 365 days2001: Unhealthy for Sensitive Groups 35 of 365 days2001: Unhealthy 9 of 365 days2002: Good 43 of 365 days2002: Moderate 265 of 365 days2002: Unhealthy for Sensitive Groups 30 of 365 days2002: Unhealthy 26 of 365 days2002: Very Unhealthy 1 of 365 days2003: Good 44 of 365 days2003: Moderate 287 of 365 days2003: Unhealthy for Sensitive Groups 27 of 365 days2003: Unhealthy 5 of 365 days2003: Very Unhealthy 2 of 365 days2004: Good 76 of 366 days2004: Moderate 266 of 366 days2004: Unhealthy for Sensitive Groups 23 of 366 days2004: Unhealthy 1 of 366 days2005: Good 188 of 365 days2005: Moderate 134 of 365 days2005: Unhealthy for Sensitive Groups 36 of 365 days2005: Unhealthy 6 of 365 days2005: Very Unhealthy 1 of 365 days20052006: Good 206 of 365 days2006: Moderate 134 of 365 days2006: Unhealthy for Sensitive Groups 23 of 365 days2006: Unhealthy 2 of 365 days2007: Good 192 of 364 days2007: Moderate 131 of 364 days2007: Unhealthy for Sensitive Groups 35 of 364 days2007: Unhealthy 6 of 364 days2008: Good 210 of 366 days2008: Moderate 137 of 366 days2008: Unhealthy for Sensitive Groups 18 of 366 days2008: Unhealthy 1 of 366 days2009: Good 238 of 360 days2009: Moderate 117 of 360 days2009: Unhealthy for Sensitive Groups 5 of 360 days2010: Good 129 of 365 days2010: Moderate 217 of 365 days2010: Unhealthy for Sensitive Groups 18 of 365 days2010: Unhealthy 1 of 365 days20102011: Good 114 of 365 days2011: Moderate 237 of 365 days2011: Unhealthy for Sensitive Groups 10 of 365 days2011: Unhealthy 4 of 365 days2012: Good 117 of 366 days2012: Moderate 225 of 366 days2012: Unhealthy for Sensitive Groups 21 of 366 days2012: Unhealthy 2 of 366 days2012: Very Unhealthy 1 of 366 days2013: Good 155 of 365 days2013: Moderate 204 of 365 days2013: Unhealthy for Sensitive Groups 6 of 365 days2014: Good 129 of 365 days2014: Moderate 230 of 365 days2014: Unhealthy for Sensitive Groups 6 of 365 days2015: Good 166 of 365 days2015: Moderate 194 of 365 days2015: Unhealthy for Sensitive Groups 5 of 365 days20152016: Good 220 of 366 days2016: Moderate 137 of 366 days2016: Unhealthy for Sensitive Groups 9 of 366 days2017: Good 227 of 365 days2017: Moderate 135 of 365 days2017: Unhealthy for Sensitive Groups 3 of 365 days2018: Good 210 of 365 days2018: Moderate 153 of 365 days2018: Unhealthy for Sensitive Groups 2 of 365 days2019: Good 157 of 365 days2019: Moderate 207 of 365 days2019: Unhealthy for Sensitive Groups 1 of 365 days2020: Good 232 of 366 days2020: Moderate 132 of 366 days2020: Unhealthy for Sensitive Groups 2 of 366 days20202021: Good 170 of 365 days2021: Moderate 195 of 365 days2022: Good 206 of 365 days2022: Moderate 157 of 365 days2022: Unhealthy for Sensitive Groups 2 of 365 days2023: Good 136 of 365 days2023: Moderate 218 of 365 days2023: Unhealthy for Sensitive Groups 7 of 365 days2023: Unhealthy 3 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 151 of 366 days2024: Moderate 211 of 366 days2024: Unhealthy for Sensitive Groups 4 of 366 days2025: Good 147 of 365 days2025: Moderate 213 of 365 days2025: Unhealthy for Sensitive Groups 4 of 365 days2025: 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 1261981: 90th percentile AQI 1001982: 90th percentile AQI 1001983: 90th percentile AQI 1121984: 90th percentile AQI 891985: 90th percentile AQI 1001986: 90th percentile AQI 771987: 90th percentile AQI 931988: 90th percentile AQI 1191989: 90th percentile AQI 871990: 90th percentile AQI 841991: 90th percentile AQI 1001992: 90th percentile AQI 631993: 90th percentile AQI 871994: 90th percentile AQI 1001995: 90th percentile AQI 901996: 90th percentile AQI 1081997: 90th percentile AQI 741998: 90th percentile AQI 1121999: 90th percentile AQI 1192000: 90th percentile AQI 932001: 90th percentile AQI 1052002: 90th percentile AQI 1292003: 90th percentile AQI 972004: 90th percentile AQI 902005: 90th percentile AQI 1052006: 90th percentile AQI 932007: 90th percentile AQI 1052008: 90th percentile AQI 842009: 90th percentile AQI 712010: 90th percentile AQI 842011: 90th percentile AQI 802012: 90th percentile AQI 902013: 90th percentile AQI 692014: 90th percentile AQI 712015: 90th percentile AQI 702016: 90th percentile AQI 662017: 90th percentile AQI 622018: 90th percentile AQI 662019: 90th percentile AQI 682020: 90th percentile AQI 612021: 90th percentile AQI 702022: 90th percentile AQI 672023: 90th percentile AQI 772024: 90th percentile AQI 722025: 90th percentile AQI 741980: Median AQI 551981: Median AQI 521982: Median AQI 491983: Median AQI 491984: Median AQI 471985: Median AQI 471986: Median AQI 441987: Median AQI 411988: Median AQI 381989: Median AQI 381990: Median AQI 351991: Median AQI 401992: Median AQI 341993: Median AQI 331994: Median AQI 351995: Median AQI 351996: Median AQI 321997: Median AQI 321998: Median AQI 351999: Median AQI 692000: Median AQI 662001: Median AQI 662002: Median AQI 642003: Median AQI 632004: Median AQI 622005: Median AQI 502006: Median AQI 472007: Median AQI 482008: Median AQI 472009: Median AQI 432010: Median AQI 562011: Median AQI 552012: Median AQI 552013: Median AQI 522014: Median AQI 542015: Median AQI 522016: Median AQI 462017: Median AQI 462018: Median AQI 472019: Median AQI 532020: Median AQI 452021: Median AQI 522022: Median AQI 482023: Median AQI 542024: Median AQI 532025: 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)26372%
Ozone9225%
Coarse particles (PM10)92%
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
202536514721341005374156PM2.5
202436615121140005372118PM2.5
202336513621873105477210PM2.5
202236520615720004867143PM2.5
202136517019500005270100PM2.5
202036623213220004561102PM2.5
201936515720710005368101PM2.5
201836521015320004766122PM2.5
201736522713530004662112PM2.5
201636622013790004666126PM2.5
201536516619450005270112PM2.5
201436512923060005471115PM2.5
201336515520460005269136PM2.5
2012366117225212105590201PM2.5
2011365114237104005580156PM2.5
2010365129217181005684156PM2.5
200936023811750004371129Ozone
2008366210137181004784174Ozone
20073641921313560048105172Ozone
2006365206134232004793154Ozone
20053651881343661050105201Ozone
200436676266231006290151PM2.5
200336544287275206397225PM2.5
20023654326530261064129214PM2.5
2001365582633590066105187PM2.5
200036660279261006693179PM2.5
19993654526045132069119232PM2.5
19983652536829150035112195Ozone
199736528956155003274177Ozone
19963662764732101032108208Ozone
199536527760225103590203Ozone
1994365269632760035100174Ozone
199336527957245003387172Ozone
199236630351120003463136Ozone
1991365257732762040100210Ozone
199036528655204003584192Ozone
198936527662207003887182Ozone
19883662725022184038119230CO
198736524291238104193220CO
1986365246102116004477192Ozone
19853652081223050047100182NO2
1984366215127186004789179NO2
198336520111432171049112201Ozone
198236520712221132049100205CO
19813651581712970052100195CO
198036615114354171055126224CO

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 Ohio with a similar median AQI in 2025

All monitored counties in Ohio

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