EnviroNearby

Butler County, Ohio air quality history

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

33%
Good days in 2025
55
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 Butler, Ohio on 365 days. 121 of those days (33%) were in the Good range, and the median daily AQI was 55. 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 283 days. Across the years with fuller monitoring, the share of Good days fell: an average of 79% in 1980–1982 versus 35% 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 366 days1980: Moderate 48 of 366 days1980: Unhealthy for Sensitive Groups 23 of 366 days1980: Unhealthy 9 of 366 days1980: Very Unhealthy 2 of 366 days19801981: Good 309 of 365 days1981: Moderate 39 of 365 days1981: Unhealthy for Sensitive Groups 13 of 365 days1981: Unhealthy 4 of 365 days1982: Good 268 of 365 days1982: Moderate 53 of 365 days1982: Unhealthy for Sensitive Groups 24 of 365 days1982: Unhealthy 16 of 365 days1982: Very Unhealthy 4 of 365 days1983: Good 264 of 364 days1983: Moderate 47 of 364 days1983: Unhealthy for Sensitive Groups 29 of 364 days1983: Unhealthy 21 of 364 days1983: Very Unhealthy 3 of 364 days1984: Good 275 of 366 days1984: Moderate 56 of 366 days1984: Unhealthy for Sensitive Groups 23 of 366 days1984: Unhealthy 8 of 366 days1984: Very Unhealthy 4 of 366 days1985: Good 281 of 365 days1985: Moderate 63 of 365 days1985: Unhealthy for Sensitive Groups 16 of 365 days1985: Unhealthy 5 of 365 days19851986: Good 212 of 303 days1986: Moderate 53 of 303 days1986: Unhealthy for Sensitive Groups 32 of 303 days1986: Unhealthy 5 of 303 days1986: Very Unhealthy 1 of 303 days1987: Good 195 of 258 days1987: Moderate 54 of 258 days1987: Unhealthy for Sensitive Groups 6 of 258 days1987: Unhealthy 3 of 258 days1988: Good 147 of 261 days1988: Moderate 60 of 261 days1988: Unhealthy for Sensitive Groups 19 of 261 days1988: Unhealthy 25 of 261 days1988: Very Unhealthy 10 of 261 days1989: Good 181 of 258 days1989: Moderate 50 of 258 days1989: Unhealthy for Sensitive Groups 21 of 258 days1989: Unhealthy 6 of 258 days1990: Good 266 of 364 days1990: Moderate 54 of 364 days1990: Unhealthy for Sensitive Groups 27 of 364 days1990: Unhealthy 15 of 364 days1990: Very Unhealthy 2 of 364 days19901991: Good 248 of 365 days1991: Moderate 65 of 365 days1991: Unhealthy for Sensitive Groups 36 of 365 days1991: Unhealthy 15 of 365 days1991: Very Unhealthy 1 of 365 days1992: Good 282 of 366 days1992: Moderate 69 of 366 days1992: Unhealthy for Sensitive Groups 10 of 366 days1992: Unhealthy 5 of 366 days1993: Good 259 of 365 days1993: Moderate 72 of 365 days1993: Unhealthy for Sensitive Groups 22 of 365 days1993: Unhealthy 11 of 365 days1993: Very Unhealthy 1 of 365 days1994: Good 247 of 364 days1994: Moderate 74 of 364 days1994: Unhealthy for Sensitive Groups 30 of 364 days1994: Unhealthy 12 of 364 days1994: Very Unhealthy 1 of 364 days1995: Good 242 of 365 days1995: Moderate 70 of 365 days1995: Unhealthy for Sensitive Groups 39 of 365 days1995: Unhealthy 13 of 365 days1995: Very Unhealthy 1 of 365 days19951996: Good 259 of 366 days1996: Moderate 65 of 366 days1996: Unhealthy for Sensitive Groups 27 of 366 days1996: Unhealthy 14 of 366 days1996: Very Unhealthy 1 of 366 days1997: Good 260 of 365 days1997: Moderate 73 of 365 days1997: Unhealthy for Sensitive Groups 25 of 365 days1997: Unhealthy 7 of 365 days1998: Good 229 of 359 days1998: Moderate 77 of 359 days1998: Unhealthy for Sensitive Groups 37 of 359 days1998: Unhealthy 15 of 359 days1998: Very Unhealthy 1 of 359 days1999: Good 82 of 363 days1999: Moderate 220 of 363 days1999: Unhealthy for Sensitive Groups 39 of 363 days1999: Unhealthy 20 of 363 days1999: Very Unhealthy 2 of 363 days2000: Good 85 of 366 days2000: Moderate 252 of 366 days2000: Unhealthy for Sensitive Groups 25 of 366 days2000: Unhealthy 4 of 366 days20002001: Good 69 of 365 days2001: Moderate 255 of 365 days2001: Unhealthy for Sensitive Groups 36 of 365 days2001: Unhealthy 5 of 365 days2002: Good 51 of 365 days2002: Moderate 263 of 365 days2002: Unhealthy for Sensitive Groups 30 of 365 days2002: Unhealthy 19 of 365 days2002: Very Unhealthy 2 of 365 days2003: Good 64 of 364 days2003: Moderate 267 of 364 days2003: Unhealthy for Sensitive Groups 28 of 364 days2003: Unhealthy 3 of 364 days2003: Very Unhealthy 2 of 364 days2004: Good 212 of 365 days2004: Moderate 137 of 365 days2004: Unhealthy for Sensitive Groups 15 of 365 days2004: Unhealthy 1 of 365 days2005: Good 132 of 311 days2005: Moderate 133 of 311 days2005: Unhealthy for Sensitive Groups 38 of 311 days2005: Unhealthy 7 of 311 days2005: Very Unhealthy 1 of 311 days20052006: Good 207 of 364 days2006: Moderate 134 of 364 days2006: Unhealthy for Sensitive Groups 22 of 364 days2006: Unhealthy 1 of 364 days2007: Good 168 of 365 days2007: Moderate 144 of 365 days2007: Unhealthy for Sensitive Groups 47 of 365 days2007: Unhealthy 6 of 365 days2008: Good 206 of 364 days2008: Moderate 141 of 364 days2008: Unhealthy for Sensitive Groups 15 of 364 days2008: Unhealthy 2 of 364 days2009: Good 217 of 363 days2009: Moderate 134 of 363 days2009: Unhealthy for Sensitive Groups 12 of 363 days2010: Good 193 of 362 days2010: Moderate 141 of 362 days2010: Unhealthy for Sensitive Groups 27 of 362 days2010: Unhealthy 1 of 362 days20102011: Good 196 of 349 days2011: Moderate 129 of 349 days2011: Unhealthy for Sensitive Groups 23 of 349 days2011: Unhealthy 1 of 349 days2012: Good 183 of 361 days2012: Moderate 146 of 361 days2012: Unhealthy for Sensitive Groups 28 of 361 days2012: Unhealthy 4 of 361 days2013: Good 232 of 365 days2013: Moderate 130 of 365 days2013: Unhealthy for Sensitive Groups 3 of 365 days2014: Good 231 of 359 days2014: Moderate 123 of 359 days2014: Unhealthy for Sensitive Groups 5 of 359 days2015: Good 237 of 360 days2015: Moderate 120 of 360 days2015: Unhealthy for Sensitive Groups 3 of 360 days20152016: Good 234 of 362 days2016: Moderate 117 of 362 days2016: Unhealthy for Sensitive Groups 11 of 362 days2017: Good 248 of 364 days2017: Moderate 110 of 364 days2017: Unhealthy for Sensitive Groups 6 of 364 days2018: Good 241 of 365 days2018: Moderate 118 of 365 days2018: Unhealthy for Sensitive Groups 6 of 365 days2019: Good 236 of 364 days2019: Moderate 126 of 364 days2019: Unhealthy for Sensitive Groups 2 of 364 days2020: Good 279 of 366 days2020: Moderate 84 of 366 days2020: Unhealthy for Sensitive Groups 3 of 366 days20202021: Good 128 of 365 days2021: Moderate 232 of 365 days2021: Unhealthy for Sensitive Groups 5 of 365 days2022: Good 146 of 365 days2022: Moderate 215 of 365 days2022: Unhealthy for Sensitive Groups 4 of 365 days2023: Good 107 of 365 days2023: Moderate 242 of 365 days2023: Unhealthy for Sensitive Groups 12 of 365 days2023: Unhealthy 4 of 365 days2024: Good 154 of 366 days2024: Moderate 209 of 366 days2024: Unhealthy for Sensitive Groups 3 of 366 days2025: Good 121 of 365 days2025: Moderate 239 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 year0501001502001980: 90th percentile AQI 931981: 90th percentile AQI 671982: 90th percentile AQI 1121983: 90th percentile AQI 1291984: 90th percentile AQI 971985: 90th percentile AQI 841986: 90th percentile AQI 1081987: 90th percentile AQI 681988: 90th percentile AQI 1661989: 90th percentile AQI 1051990: 90th percentile AQI 1151991: 90th percentile AQI 1151992: 90th percentile AQI 741993: 90th percentile AQI 971994: 90th percentile AQI 1081995: 90th percentile AQI 1151996: 90th percentile AQI 1051997: 90th percentile AQI 931998: 90th percentile AQI 1221999: 90th percentile AQI 1262000: 90th percentile AQI 972001: 90th percentile AQI 1052002: 90th percentile AQI 1192003: 90th percentile AQI 932004: 90th percentile AQI 842005: 90th percentile AQI 1192006: 90th percentile AQI 902007: 90th percentile AQI 1122008: 90th percentile AQI 842009: 90th percentile AQI 772010: 90th percentile AQI 932011: 90th percentile AQI 912012: 90th percentile AQI 1002013: 90th percentile AQI 712014: 90th percentile AQI 712015: 90th percentile AQI 732016: 90th percentile AQI 752017: 90th percentile AQI 682018: 90th percentile AQI 712019: 90th percentile AQI 702020: 90th percentile AQI 612021: 90th percentile AQI 752022: 90th percentile AQI 712023: 90th percentile AQI 802024: 90th percentile AQI 692025: 90th percentile AQI 771980: Median AQI 351981: Median AQI 321982: Median AQI 361983: Median AQI 331984: Median AQI 321985: Median AQI 331986: Median AQI 371987: Median AQI 391988: Median AQI 481989: Median AQI 421990: Median AQI 381991: Median AQI 411992: Median AQI 381993: Median AQI 381994: Median AQI 401995: Median AQI 401996: Median AQI 391997: Median AQI 391998: Median AQI 421999: Median AQI 672000: Median AQI 642001: Median AQI 662002: Median AQI 642003: Median AQI 612004: Median AQI 452005: Median AQI 572006: Median AQI 462007: Median AQI 522008: Median AQI 472009: Median AQI 452010: Median AQI 492011: Median AQI 472012: Median AQI 502013: Median AQI 442014: Median AQI 442015: Median AQI 442016: Median AQI 442017: Median AQI 432018: Median AQI 422019: Median AQI 442020: Median AQI 412021: Median AQI 552022: Median AQI 532023: Median AQI 562024: Median AQI 532025: Median AQI 551980198519901995200020052010201520202025
  • 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)28378%
Ozone8222%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536512123941005577151PM2.5
202436615420930005369122PM2.5
2023365107242124005680197PM2.5
202236514621540005371119PM2.5
202136512823250005575116PM2.5
20203662798430004161126Ozone
201936423612620004470101Ozone
201836524111860004271140Ozone
201736424811060004368126Ozone
2016362234117110004475136Ozone
201536023712030004473112Ozone
201435923112350004471133Ozone
201336523213030004471119Ozone
20123611831462840050100179Ozone
2011349196129231004791172Ozone
2010362193141271004993151Ozone
2009363217134120004577129Ozone
2008364206141152004784164Ozone
20073651681444760052112197Ozone
2006364207134221004690154Ozone
20053111321333871057119201Ozone
2004365212137151004584161Ozone
200336464267283206193217PM2.5
20023655126330192064119208PM2.5
2001365692553650066105195PM2.5
200036685252254006497195PM2.5
19993638222039202067126221Ozone
19983592297737151042122206Ozone
199736526073257003993195Ozone
19963662596527141039105203Ozone
19953652427039131040115217Ozone
19943642477430121040108206Ozone
1993365259722211103897205Ozone
199236628269105003874166Ozone
19913652486536151041115204Ozone
19903642665427152038115213Ozone
1989258181502160042105187Ozone
198826114760192510048166221Ozone
19872581955463003968197Ozone
1986303212533251037108225Ozone
198536528163165003384197Ozone
198436627556238403297203Ozone
19833642644729213033129207Ozone
19823652685324164036112207Ozone
198136530939134003267174Ozone
198036628448239203593216Ozone

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