EnviroNearby

Harrison County, Iowa air quality history

Daily Air Quality Index summaries from EPA monitors in Harrison, Iowa, 1997–2025.

83%
Good days in 2025
39
Median daily AQI, 2025
2
Days above 100 in 2025
236
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Harrison, Iowa on 236 days. 196 of those days (83%) were in the Good range, and the median daily AQI was 39. That median is lower than the typical monitored county in Iowa (median 43.5 across 14 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 236 days. Across the years with fuller monitoring, the share of Good days rose: an average of 74% in 1997–1999 versus 79% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (236 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%1997: Good 161 of 212 days1997: Moderate 50 of 212 days1997: Unhealthy for Sensitive Groups 1 of 212 days19971998: Good 147 of 205 days1998: Moderate 51 of 205 days1998: Unhealthy for Sensitive Groups 6 of 205 days1998: Unhealthy 1 of 205 days1999: Good 156 of 206 days1999: Moderate 47 of 206 days1999: Unhealthy for Sensitive Groups 3 of 206 days2000: Good 164 of 213 days2000: Moderate 39 of 213 days2000: Unhealthy for Sensitive Groups 10 of 213 days2001: Good 177 of 211 days2001: Moderate 28 of 211 days2001: Unhealthy for Sensitive Groups 6 of 211 days2002: Good 137 of 213 days2002: Moderate 61 of 213 days2002: Unhealthy for Sensitive Groups 14 of 213 days2002: Unhealthy 1 of 213 days20022003: Good 135 of 214 days2003: Moderate 69 of 214 days2003: Unhealthy for Sensitive Groups 10 of 214 days2004: Good 156 of 197 days2004: Moderate 37 of 197 days2004: Unhealthy for Sensitive Groups 4 of 197 days2005: Good 140 of 214 days2005: Moderate 59 of 214 days2005: Unhealthy for Sensitive Groups 15 of 214 days2006: Good 147 of 214 days2006: Moderate 57 of 214 days2006: Unhealthy for Sensitive Groups 10 of 214 days2007: Good 175 of 214 days2007: Moderate 37 of 214 days2007: Unhealthy for Sensitive Groups 2 of 214 days20072008: Good 192 of 214 days2008: Moderate 22 of 214 days2009: Good 190 of 214 days2009: Moderate 23 of 214 days2009: Unhealthy for Sensitive Groups 1 of 214 days2010: Good 180 of 213 days2010: Moderate 31 of 213 days2010: Unhealthy for Sensitive Groups 2 of 213 days2011: Good 170 of 213 days2011: Moderate 42 of 213 days2011: Unhealthy for Sensitive Groups 1 of 213 days2012: Good 135 of 212 days2012: Moderate 64 of 212 days2012: Unhealthy for Sensitive Groups 13 of 212 days20122013: Good 184 of 213 days2013: Moderate 29 of 213 days2014: Good 186 of 212 days2014: Moderate 26 of 212 days2015: Good 191 of 214 days2015: Moderate 22 of 214 days2015: Unhealthy for Sensitive Groups 1 of 214 days2016: Good 188 of 212 days2016: Moderate 24 of 212 days2017: Good 207 of 244 days2017: Moderate 37 of 244 days20172018: Good 213 of 245 days2018: Moderate 30 of 245 days2018: Unhealthy for Sensitive Groups 2 of 245 days2019: Good 222 of 241 days2019: Moderate 19 of 241 days2020: Good 223 of 242 days2020: Moderate 19 of 242 days2021: Good 216 of 243 days2021: Moderate 27 of 243 days2022: Good 210 of 237 days2022: Moderate 27 of 237 days20222023: Good 163 of 238 days2023: Moderate 59 of 238 days2023: Unhealthy for Sensitive Groups 16 of 238 days2024: Good 208 of 244 days2024: Moderate 36 of 244 days2025: Good 196 of 236 days2025: Moderate 38 of 236 days2025: Unhealthy for Sensitive Groups 2 of 236 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 year0501001997: 90th percentile AQI 641998: 90th percentile AQI 741999: 90th percentile AQI 772000: 90th percentile AQI 772001: 90th percentile AQI 672002: 90th percentile AQI 902003: 90th percentile AQI 902004: 90th percentile AQI 712005: 90th percentile AQI 972006: 90th percentile AQI 872007: 90th percentile AQI 642008: 90th percentile AQI 512009: 90th percentile AQI 512010: 90th percentile AQI 612011: 90th percentile AQI 642012: 90th percentile AQI 932013: 90th percentile AQI 512014: 90th percentile AQI 542015: 90th percentile AQI 512016: 90th percentile AQI 512017: 90th percentile AQI 582018: 90th percentile AQI 582019: 90th percentile AQI 502020: 90th percentile AQI 492021: 90th percentile AQI 542022: 90th percentile AQI 512023: 90th percentile AQI 902024: 90th percentile AQI 542025: 90th percentile AQI 641997: Median AQI 411998: Median AQI 431999: Median AQI 422000: Median AQI 422001: Median AQI 392002: Median AQI 442003: Median AQI 452004: Median AQI 412005: Median AQI 452006: Median AQI 442007: Median AQI 412008: Median AQI 412009: Median AQI 402010: Median AQI 402011: Median AQI 402012: Median AQI 462013: Median AQI 422014: Median AQI 382015: Median AQI 402016: Median AQI 372017: Median AQI 392018: Median AQI 392019: Median AQI 382020: Median AQI 372021: Median AQI 392022: Median AQI 402023: Median AQI 442024: Median AQI 422025: Median AQI 391997200220072012201720222025
  • 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
Ozone236100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20252361963820003964119Ozone
2024244208360000425490Ozone
202323816359160004490140Ozone
2022237210270000405184Ozone
2021243216270000395487Ozone
2020242223190000374987Ozone
2019241222190000385097Ozone
20182452133020003958101Ozone
2017244207370000395887Ozone
2016212188240000375184Ozone
20152141912210004051108Ozone
2014212186260000385490Ozone
2013213184290000425190Ozone
201221213564130004693133Ozone
20112131704210004064112Ozone
20102131803120004061122Ozone
20092141902310004051101Ozone
2008214192220000415193Ozone
20072141753720004164150Ozone
200621414757100004487122Ozone
200521414059150004597143Ozone
20041971563740004171129Ozone
200321413569100004590126Ozone
200221313761141004490151Ozone
20012111772860003967147Ozone
200021316439100004277122Ozone
19992061564730004277122Ozone
19982051475161004374159Ozone
19972121615010004164105Ozone

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 Iowa with a similar median AQI in 2025

All monitored counties in Iowa

Source: U.S. EPA AirData, “Annual AQI by County” files for 1997–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem