EnviroNearby

Montgomery County, Ohio air quality history

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

60%
Good days in 2025
46
Median daily AQI, 2025
4
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 Montgomery, Ohio on 365 days. 220 of those days (60%) were in the Good range, and the median daily AQI was 46. 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 233 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 60% in 1980–1982 versus 57% 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 237 of 366 days1980: Moderate 87 of 366 days1980: Unhealthy for Sensitive Groups 25 of 366 days1980: Unhealthy 14 of 366 days1980: Very Unhealthy 3 of 366 days19801981: Good 215 of 365 days1981: Moderate 103 of 365 days1981: Unhealthy for Sensitive Groups 30 of 365 days1981: Unhealthy 15 of 365 days1981: Very Unhealthy 2 of 365 days1982: Good 201 of 365 days1982: Moderate 110 of 365 days1982: Unhealthy for Sensitive Groups 25 of 365 days1982: Unhealthy 23 of 365 days1982: Very Unhealthy 6 of 365 days1983: Good 221 of 365 days1983: Moderate 91 of 365 days1983: Unhealthy for Sensitive Groups 27 of 365 days1983: Unhealthy 23 of 365 days1983: Very Unhealthy 3 of 365 days1984: Good 245 of 366 days1984: Moderate 84 of 366 days1984: Unhealthy for Sensitive Groups 30 of 366 days1984: Unhealthy 7 of 366 days1985: Good 254 of 365 days1985: Moderate 94 of 365 days1985: Unhealthy for Sensitive Groups 13 of 365 days1985: Unhealthy 4 of 365 days19851986: Good 262 of 365 days1986: Moderate 73 of 365 days1986: Unhealthy for Sensitive Groups 21 of 365 days1986: Unhealthy 7 of 365 days1986: Very Unhealthy 2 of 365 days1987: Good 264 of 365 days1987: Moderate 65 of 365 days1987: Unhealthy for Sensitive Groups 30 of 365 days1987: Unhealthy 6 of 365 days1988: Good 274 of 366 days1988: Moderate 50 of 366 days1988: Unhealthy for Sensitive Groups 20 of 366 days1988: Unhealthy 20 of 366 days1988: Very Unhealthy 2 of 366 days1989: Good 307 of 365 days1989: Moderate 47 of 365 days1989: Unhealthy for Sensitive Groups 10 of 365 days1989: Unhealthy 1 of 365 days1990: Good 312 of 365 days1990: Moderate 30 of 365 days1990: Unhealthy for Sensitive Groups 18 of 365 days1990: Unhealthy 4 of 365 days1990: Very Unhealthy 1 of 365 days19901991: Good 303 of 365 days1991: Moderate 36 of 365 days1991: Unhealthy for Sensitive Groups 22 of 365 days1991: Unhealthy 4 of 365 days1992: Good 344 of 366 days1992: Moderate 19 of 366 days1992: Unhealthy for Sensitive Groups 2 of 366 days1992: Unhealthy 1 of 366 days1993: Good 282 of 365 days1993: Moderate 58 of 365 days1993: Unhealthy for Sensitive Groups 15 of 365 days1993: Unhealthy 10 of 365 days1994: Good 257 of 365 days1994: Moderate 70 of 365 days1994: Unhealthy for Sensitive Groups 29 of 365 days1994: Unhealthy 9 of 365 days1995: Good 289 of 365 days1995: Moderate 54 of 365 days1995: Unhealthy for Sensitive Groups 16 of 365 days1995: Unhealthy 6 of 365 days19951996: Good 279 of 366 days1996: Moderate 52 of 366 days1996: Unhealthy for Sensitive Groups 21 of 366 days1996: Unhealthy 13 of 366 days1996: Very Unhealthy 1 of 366 days1997: Good 291 of 365 days1997: Moderate 52 of 365 days1997: Unhealthy for Sensitive Groups 18 of 365 days1997: Unhealthy 3 of 365 days1997: Very Unhealthy 1 of 365 days1998: Good 263 of 365 days1998: Moderate 62 of 365 days1998: Unhealthy for Sensitive Groups 31 of 365 days1998: Unhealthy 9 of 365 days1999: Good 72 of 365 days1999: Moderate 251 of 365 days1999: Unhealthy for Sensitive Groups 33 of 365 days1999: Unhealthy 7 of 365 days1999: Very Unhealthy 2 of 365 days2000: Good 64 of 366 days2000: Moderate 277 of 366 days2000: Unhealthy for Sensitive Groups 23 of 366 days2000: Unhealthy 2 of 366 days20002001: Good 74 of 365 days2001: Moderate 257 of 365 days2001: Unhealthy for Sensitive Groups 31 of 365 days2001: Unhealthy 3 of 365 days2002: Good 56 of 365 days2002: Moderate 270 of 365 days2002: Unhealthy for Sensitive Groups 25 of 365 days2002: Unhealthy 13 of 365 days2002: Very Unhealthy 1 of 365 days2003: Good 66 of 365 days2003: Moderate 271 of 365 days2003: Unhealthy for Sensitive Groups 23 of 365 days2003: Unhealthy 3 of 365 days2003: Very Unhealthy 2 of 365 days2004: Good 241 of 366 days2004: Moderate 122 of 366 days2004: Unhealthy for Sensitive Groups 3 of 366 days2005: Good 214 of 365 days2005: Moderate 124 of 365 days2005: Unhealthy for Sensitive Groups 26 of 365 days2005: Unhealthy 1 of 365 days20052006: Good 240 of 365 days2006: Moderate 118 of 365 days2006: Unhealthy for Sensitive Groups 7 of 365 days2007: Good 225 of 365 days2007: Moderate 124 of 365 days2007: Unhealthy for Sensitive Groups 15 of 365 days2007: Unhealthy 1 of 365 days2008: Good 99 of 366 days2008: Moderate 252 of 366 days2008: Unhealthy for Sensitive Groups 14 of 366 days2008: Unhealthy 1 of 366 days2009: Good 203 of 365 days2009: Moderate 155 of 365 days2009: Unhealthy for Sensitive Groups 7 of 365 days2010: Good 118 of 365 days2010: Moderate 226 of 365 days2010: Unhealthy for Sensitive Groups 21 of 365 days20102011: Good 132 of 365 days2011: Moderate 216 of 365 days2011: Unhealthy for Sensitive Groups 16 of 365 days2011: Unhealthy 1 of 365 days2012: Good 125 of 366 days2012: Moderate 224 of 366 days2012: Unhealthy for Sensitive Groups 16 of 366 days2012: Unhealthy 1 of 366 days2013: Good 137 of 365 days2013: Moderate 223 of 365 days2013: Unhealthy for Sensitive Groups 5 of 365 days2014: Good 159 of 365 days2014: Moderate 204 of 365 days2014: Unhealthy for Sensitive Groups 2 of 365 days2015: Good 195 of 365 days2015: Moderate 167 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days20152016: Good 227 of 366 days2016: Moderate 133 of 366 days2016: Unhealthy for Sensitive Groups 6 of 366 days2017: Good 242 of 365 days2017: Moderate 122 of 365 days2017: Unhealthy for Sensitive Groups 1 of 365 days2018: Good 193 of 363 days2018: Moderate 166 of 363 days2018: Unhealthy for Sensitive Groups 4 of 363 days2019: Good 163 of 365 days2019: Moderate 202 of 365 days2020: Good 177 of 361 days2020: Moderate 180 of 361 days2020: Unhealthy for Sensitive Groups 4 of 361 days20202021: Good 157 of 357 days2021: Moderate 199 of 357 days2021: Unhealthy for Sensitive Groups 1 of 357 days2022: Good 205 of 365 days2022: Moderate 158 of 365 days2022: Unhealthy for Sensitive Groups 2 of 365 days2023: Good 181 of 363 days2023: Moderate 171 of 363 days2023: Unhealthy for Sensitive Groups 8 of 363 days2023: Unhealthy 3 of 363 days2024: Good 225 of 364 days2024: Moderate 135 of 364 days2024: Unhealthy for Sensitive Groups 4 of 364 days2025: Good 220 of 365 days2025: Moderate 141 of 365 days2025: Unhealthy for Sensitive Groups 4 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 1031981: 90th percentile AQI 1051982: 90th percentile AQI 1331983: 90th percentile AQI 1261984: 90th percentile AQI 1011985: 90th percentile AQI 841986: 90th percentile AQI 901987: 90th percentile AQI 1001988: 90th percentile AQI 1151989: 90th percentile AQI 671990: 90th percentile AQI 741991: 90th percentile AQI 841992: 90th percentile AQI 461993: 90th percentile AQI 841994: 90th percentile AQI 1011995: 90th percentile AQI 841996: 90th percentile AQI 1001997: 90th percentile AQI 801998: 90th percentile AQI 1051999: 90th percentile AQI 1052000: 90th percentile AQI 962001: 90th percentile AQI 1002002: 90th percentile AQI 1062003: 90th percentile AQI 952004: 90th percentile AQI 742005: 90th percentile AQI 932006: 90th percentile AQI 742007: 90th percentile AQI 792008: 90th percentile AQI 842009: 90th percentile AQI 752010: 90th percentile AQI 882011: 90th percentile AQI 872012: 90th percentile AQI 842013: 90th percentile AQI 712014: 90th percentile AQI 732015: 90th percentile AQI 672016: 90th percentile AQI 672017: 90th percentile AQI 642018: 90th percentile AQI 662019: 90th percentile AQI 672020: 90th percentile AQI 672021: 90th percentile AQI 712022: 90th percentile AQI 642023: 90th percentile AQI 712024: 90th percentile AQI 642025: 90th percentile AQI 671980: Median AQI 431981: Median AQI 441982: Median AQI 481983: Median AQI 441984: Median AQI 441985: Median AQI 411986: Median AQI 391987: Median AQI 381988: Median AQI 361989: Median AQI 341990: Median AQI 271991: Median AQI 281992: Median AQI 271993: Median AQI 301994: Median AQI 351995: Median AQI 311996: Median AQI 301997: Median AQI 291998: Median AQI 321999: Median AQI 652000: Median AQI 662001: Median AQI 652002: Median AQI 612003: Median AQI 612004: Median AQI 392005: Median AQI 442006: Median AQI 402007: Median AQI 442008: Median AQI 572009: Median AQI 482010: Median AQI 592011: Median AQI 552012: Median AQI 552013: Median AQI 542014: Median AQI 532015: Median AQI 482016: Median AQI 462017: Median AQI 442018: Median AQI 492019: Median AQI 522020: Median AQI 512021: Median AQI 532022: Median AQI 482023: Median AQI 512024: 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)23364%
Ozone13236%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536522014140004667129PM2.5
202436422513540004764147PM2.5
202336318117183005171196PM2.5
202236520515820004864126PM2.5
202135715719910005371101PM2.5
202036117718040005167112PM2.5
20193651632020000526795PM2.5
201836319316640004966129PM2.5
201736524212210004464101PM2.5
201636622713360004667112PM2.5
201536519516730004867108PM2.5
201436515920420005373112PM2.5
201336513722350005471113PM2.5
2012366125224161005584169PM2.5
2011365132216161005587172PM2.5
2010365118226210005988140PM2.5
200936520315570004875129Ozone
200836699252141005784174PM2.5
2007365225124151004479154Ozone
200636524011870004074147Ozone
2005365214124261004493174Ozone
200436624112230003974117Ozone
200336566271233206195217PM2.5
20023655627025131061106204PM2.5
2001365742573130065100172PM2.5
200036664277232006696192PM2.5
1999365722513372065105207PM2.5
1998365263623190032105179Ozone
199736529152183102980201Ozone
19963662795221131030100207Ozone
199536528954166003184195Ozone
1994365257702990035101200Ozone
1993365282581510003084182Ozone
19923663441921002746154Ozone
199136530336224002884185Ozone
199036531230184102774203Ozone
198936530747101003467156CO
19883662745020202036115208Ozone
1987365264653060038100182Ozone
198636526273217203990217Ozone
198536525494134004184164NO2
1984366245843070044101200NO2
19833652219127233044126209Ozone
198236520111025236048133218NO2
198136521510330152044105208Ozone
19803662378725143043103208Ozone

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