EnviroNearby

Adams County, Ohio air quality history

Daily Air Quality Index summaries from EPA monitors in Adams, Ohio, 1987–2020.

75%
Good days in 2020
39
Median daily AQI, 2020
0
Days above 100 in 2020
287
Days with an AQI in 2020 (of 366)

In 2020, EPA reported a daily Air Quality Index (AQI) for Adams, Ohio on 287 days. 215 of those days (75%) were in the Good range, and the median daily AQI was 39. That median is about the same as the typical monitored county in Ohio (median 39.5 across 38 counties), and about the same as the typical monitored U.S. county (39). The main pollutant was fine particles (PM2.5) on 287 days. Across the years with fuller monitoring, the share of Good days rose: an average of 73% in 1994–2010 versus 84% in 2018–2020.

EPA did not report an AQI for every day of 2020 here (287 of 366 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.

The most recent year with data for this county is 2020; EPA's files for 2021–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1988, 1989, 1990, 1991, 1992, 1993…) are shown in the table but left out of comparisons and trend statements.

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%1987: Good 30 of 31 days1987: Moderate 1 of 31 days19871988: Good 57 of 59 days1988: Moderate 2 of 59 days1989: Good 57 of 61 days1989: Moderate 4 of 61 days19891990: Good 59 of 61 days1990: Moderate 2 of 61 days1991: Good 58 of 58 days19911992: Good 59 of 59 days1993: Good 58 of 59 days1993: Moderate 1 of 59 days19931994: Good 134 of 134 days1995: Good 301 of 305 days1995: Moderate 3 of 305 days1995: Unhealthy for Sensitive Groups 1 of 305 days19952010: Good 38 of 178 days2010: Moderate 140 of 178 days2011: Good 170 of 319 days2011: Moderate 147 of 319 days2011: Unhealthy for Sensitive Groups 2 of 319 days20112012: Good 241 of 366 days2012: Moderate 125 of 366 days2013: Good 261 of 362 days2013: Moderate 101 of 362 days20132014: Good 278 of 359 days2014: Moderate 81 of 359 days2015: Good 292 of 353 days2015: Moderate 61 of 353 days20152016: Good 339 of 366 days2016: Moderate 27 of 366 days2017: Good 341 of 365 days2017: Moderate 24 of 365 days20172018: Good 288 of 333 days2018: Moderate 45 of 333 days2019: Good 294 of 327 days2019: Moderate 33 of 327 days20192020: Good 215 of 287 days2020: Moderate 72 of 287 days2020
  • 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 year0501001987: 90th percentile AQI 361988: 90th percentile AQI 431989: 90th percentile AQI 411990: 90th percentile AQI 381991: 90th percentile AQI 341992: 90th percentile AQI 331993: 90th percentile AQI 371994: 90th percentile AQI 261995: 90th percentile AQI 272010: 90th percentile AQI 732011: 90th percentile AQI 732012: 90th percentile AQI 582013: 90th percentile AQI 562014: 90th percentile AQI 552015: 90th percentile AQI 542016: 90th percentile AQI 492017: 90th percentile AQI 472018: 90th percentile AQI 532019: 90th percentile AQI 512020: 90th percentile AQI 551987: Median AQI 181988: Median AQI 211989: Median AQI 201990: Median AQI 191991: Median AQI 191992: Median AQI 191993: Median AQI 161994: Median AQI 131995: Median AQI 112010: Median AQI 572011: Median AQI 472012: Median AQI 422013: Median AQI 382014: Median AQI 362015: Median AQI 322016: Median AQI 312017: Median AQI 302018: Median AQI 312019: Median AQI 282020: Median AQI 3919871989199119931995201120132015201720192020
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2020

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)287100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2020287215720000395583PM2.5
2019327294330000285166PM2.5
2018333288450000315370PM2.5
2017365341240000304787PM2.5
2016366339270000314973PM2.5
2015353292610000325473PM2.5
2014359278810000365571PM2.5
20133622611010000385674PM2.5
20123662411250000425876PM2.5
201131917014720004773105PM2.5
2010178381400000577398PM2.5
1995305301310001127103NO2
199413413400000132639NO2
1993595810000163756PM10
1992595900000193344PM10
1991585800000193449PM10
1990615920000193857PM10
1989615740000204159PM10
1988595720000214362PM10
1987313010000183656PM10

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.

All monitored counties in Ohio

Source: U.S. EPA AirData, “Annual AQI by County” files for 1987–2020 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem