EnviroNearby

Miami County, Ohio air quality history

Daily Air Quality Index summaries from EPA monitors in Miami, Ohio, 1993–2025.

84%
Good days in 2025
40
Median daily AQI, 2025
1
Days above 100 in 2025
240
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Miami, Ohio on 240 days. 202 of those days (84%) were in the Good range, and the median daily AQI was 40. That median is lower than the typical monitored county in Ohio (median 43 across 36 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 240 days. Across the years with fuller monitoring, the share of Good days rose: an average of 72% in 1993–1995 versus 81% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (240 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

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%1993: Good 131 of 197 days1993: Moderate 52 of 197 days1993: Unhealthy for Sensitive Groups 11 of 197 days1993: Unhealthy 3 of 197 days19931994: Good 182 of 213 days1994: Moderate 30 of 213 days1994: Unhealthy 1 of 213 days1995: Good 135 of 214 days1995: Moderate 58 of 214 days1995: Unhealthy for Sensitive Groups 18 of 214 days1995: Unhealthy 3 of 214 days1996: Good 123 of 211 days1996: Moderate 58 of 211 days1996: Unhealthy for Sensitive Groups 23 of 211 days1996: Unhealthy 6 of 211 days1996: Very Unhealthy 1 of 211 days1997: Good 137 of 210 days1997: Moderate 49 of 210 days1997: Unhealthy for Sensitive Groups 19 of 210 days1997: Unhealthy 5 of 210 days1998: Good 113 of 210 days1998: Moderate 66 of 210 days1998: Unhealthy for Sensitive Groups 22 of 210 days1998: Unhealthy 9 of 210 days19981999: Good 122 of 208 days1999: Moderate 55 of 208 days1999: Unhealthy for Sensitive Groups 24 of 208 days1999: Unhealthy 7 of 208 days2000: Good 137 of 214 days2000: Moderate 64 of 214 days2000: Unhealthy for Sensitive Groups 10 of 214 days2000: Unhealthy 3 of 214 days2001: Good 121 of 214 days2001: Moderate 81 of 214 days2001: Unhealthy for Sensitive Groups 11 of 214 days2001: Unhealthy 1 of 214 days2002: Good 103 of 210 days2002: Moderate 65 of 210 days2002: Unhealthy for Sensitive Groups 27 of 210 days2002: Unhealthy 15 of 210 days2003: Good 120 of 214 days2003: Moderate 75 of 214 days2003: Unhealthy for Sensitive Groups 14 of 214 days2003: Unhealthy 3 of 214 days2003: Very Unhealthy 2 of 214 days20032004: Good 148 of 213 days2004: Moderate 57 of 213 days2004: Unhealthy for Sensitive Groups 8 of 213 days2005: Good 132 of 214 days2005: Moderate 62 of 214 days2005: Unhealthy for Sensitive Groups 20 of 214 days2006: Good 148 of 213 days2006: Moderate 59 of 213 days2006: Unhealthy for Sensitive Groups 5 of 213 days2006: Unhealthy 1 of 213 days2007: Good 147 of 214 days2007: Moderate 57 of 214 days2007: Unhealthy for Sensitive Groups 10 of 214 days2008: Good 153 of 214 days2008: Moderate 58 of 214 days2008: Unhealthy for Sensitive Groups 3 of 214 days20082009: Good 172 of 214 days2009: Moderate 38 of 214 days2009: Unhealthy for Sensitive Groups 4 of 214 days2010: Good 146 of 213 days2010: Moderate 65 of 213 days2010: Unhealthy for Sensitive Groups 2 of 213 days2011: Good 145 of 214 days2011: Moderate 62 of 214 days2011: Unhealthy for Sensitive Groups 7 of 214 days2012: Good 131 of 213 days2012: Moderate 68 of 213 days2012: Unhealthy for Sensitive Groups 13 of 213 days2012: Unhealthy 1 of 213 days2013: Good 175 of 214 days2013: Moderate 37 of 214 days2013: Unhealthy for Sensitive Groups 2 of 214 days20132014: Good 181 of 214 days2014: Moderate 32 of 214 days2014: Unhealthy for Sensitive Groups 1 of 214 days2015: Good 177 of 213 days2015: Moderate 34 of 213 days2015: Unhealthy for Sensitive Groups 2 of 213 days2016: Good 164 of 213 days2016: Moderate 46 of 213 days2016: Unhealthy for Sensitive Groups 3 of 213 days2017: Good 210 of 245 days2017: Moderate 34 of 245 days2017: Unhealthy for Sensitive Groups 1 of 245 days2018: Good 207 of 245 days2018: Moderate 37 of 245 days2018: Unhealthy for Sensitive Groups 1 of 245 days20182019: Good 226 of 241 days2019: Moderate 15 of 241 days2020: Good 217 of 229 days2020: Moderate 12 of 229 days2021: Good 215 of 245 days2021: Moderate 30 of 245 days2022: Good 214 of 245 days2022: Moderate 29 of 245 days2022: Unhealthy for Sensitive Groups 2 of 245 days2023: Good 193 of 244 days2023: Moderate 48 of 244 days2023: Unhealthy for Sensitive Groups 3 of 244 days20232024: Good 198 of 245 days2024: Moderate 46 of 245 days2024: Unhealthy for Sensitive Groups 1 of 245 days2025: Good 202 of 240 days2025: Moderate 37 of 240 days2025: Unhealthy for Sensitive Groups 1 of 240 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 year0501001501993: 90th percentile AQI 931994: 90th percentile AQI 611995: 90th percentile AQI 1001996: 90th percentile AQI 1261997: 90th percentile AQI 1011998: 90th percentile AQI 1151999: 90th percentile AQI 1122000: 90th percentile AQI 872001: 90th percentile AQI 932002: 90th percentile AQI 1432003: 90th percentile AQI 972004: 90th percentile AQI 772005: 90th percentile AQI 932006: 90th percentile AQI 772007: 90th percentile AQI 842008: 90th percentile AQI 742009: 90th percentile AQI 672010: 90th percentile AQI 772011: 90th percentile AQI 802012: 90th percentile AQI 902013: 90th percentile AQI 612014: 90th percentile AQI 582015: 90th percentile AQI 612016: 90th percentile AQI 672017: 90th percentile AQI 582018: 90th percentile AQI 612019: 90th percentile AQI 492020: 90th percentile AQI 492021: 90th percentile AQI 542022: 90th percentile AQI 512023: 90th percentile AQI 672024: 90th percentile AQI 612025: 90th percentile AQI 611993: Median AQI 441994: Median AQI 351995: Median AQI 451996: Median AQI 471997: Median AQI 441998: Median AQI 491999: Median AQI 472000: Median AQI 462001: Median AQI 482002: Median AQI 512003: Median AQI 482004: Median AQI 442005: Median AQI 462006: Median AQI 442007: Median AQI 452008: Median AQI 442009: Median AQI 412010: Median AQI 442011: Median AQI 452012: Median AQI 472013: Median AQI 422014: Median AQI 412015: Median AQI 422016: Median AQI 432017: Median AQI 402018: Median AQI 402019: Median AQI 402020: Median AQI 392021: Median AQI 402022: Median AQI 392023: Median AQI 432024: Median AQI 432025: Median AQI 4019931998200320082013201820232025
  • 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
Ozone240100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20252402023710004061101Ozone
20242451984610004361101Ozone
20232441934830004367112Ozone
20222452142920003951122Ozone
2021245215300000405487Ozone
2020229217120000394993Ozone
2019241226150000404977Ozone
20182452073710004061140Ozone
20172452103410004058101Ozone
20162131644630004367101Ozone
20152131773420004261105Ozone
20142141813210004158105Ozone
20132141753720004261105Ozone
201221313168131004790177Ozone
20112141456270004580126Ozone
20102131466520004477133Ozone
20092141723840004167105Ozone
20082141535830004474112Ozone
200721414757100004584143Ozone
20062131485951004477156Ozone
200521413262200004693150Ozone
20042131485780004477133Ozone
200321412075143204897210Ozone
20022101036527150051143192Ozone
200121412181111004893177Ozone
200021413764103004687192Ozone
1999208122552470047112197Ozone
1998210113662290049115182Ozone
1997210137491950044101182Ozone
1996211123582361047126201Ozone
1995214135581830045100187Ozone
19942131823001003561154Ozone
199319713152113004493161Ozone

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 1993–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem