EnviroNearby

Clinton County, Iowa air quality history

Daily Air Quality Index summaries from EPA monitors in Clinton, Iowa, 1985–2025.

59%
Good days in 2025
45
Median daily AQI, 2025
3
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 Clinton, Iowa on 365 days. 217 of those days (59%) were in the Good range, and the median daily AQI was 45. That median is about the same as the typical monitored county in Iowa (median 43.5 across 14 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 227 days. Across the years with fuller monitoring, the share of Good days fell: an average of 84% in 1986–1988 versus 53% in 2023–2025.

Years with fewer than 120 monitored days (1985) 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%1985: Good 25 of 26 days1985: Moderate 1 of 26 days19851986: Good 143 of 171 days1986: Moderate 28 of 171 days1987: Good 161 of 182 days1987: Moderate 21 of 182 days1988: Good 144 of 178 days1988: Moderate 34 of 178 days1989: Good 156 of 172 days1989: Moderate 16 of 172 days1990: Good 157 of 177 days1990: Moderate 20 of 177 days19901991: Good 162 of 178 days1991: Moderate 16 of 178 days1992: Good 131 of 146 days1992: Moderate 15 of 146 days1993: Good 167 of 173 days1993: Moderate 6 of 173 days1994: Good 267 of 290 days1994: Moderate 23 of 290 days1995: Good 313 of 358 days1995: Moderate 45 of 358 days19951996: Good 332 of 351 days1996: Moderate 19 of 351 days1997: Good 324 of 348 days1997: Moderate 24 of 348 days1998: Good 335 of 348 days1998: Moderate 13 of 348 days1999: Good 232 of 361 days1999: Moderate 112 of 361 days1999: Unhealthy for Sensitive Groups 14 of 361 days1999: Unhealthy 3 of 361 days2000: Good 247 of 357 days2000: Moderate 105 of 357 days2000: Unhealthy for Sensitive Groups 5 of 357 days20002001: Good 252 of 362 days2001: Moderate 98 of 362 days2001: Unhealthy for Sensitive Groups 12 of 362 days2002: Good 252 of 365 days2002: Moderate 97 of 365 days2002: Unhealthy for Sensitive Groups 15 of 365 days2002: Unhealthy 1 of 365 days2003: Good 255 of 363 days2003: Moderate 94 of 363 days2003: Unhealthy for Sensitive Groups 14 of 363 days2004: Good 274 of 361 days2004: Moderate 82 of 361 days2004: Unhealthy for Sensitive Groups 5 of 361 days2005: Good 197 of 323 days2005: Moderate 107 of 323 days2005: Unhealthy for Sensitive Groups 18 of 323 days2005: Unhealthy 1 of 323 days20052006: Good 146 of 262 days2006: Moderate 113 of 262 days2006: Unhealthy for Sensitive Groups 3 of 262 days2007: Good 124 of 358 days2007: Moderate 221 of 358 days2007: Unhealthy for Sensitive Groups 13 of 358 days2008: Good 133 of 364 days2008: Moderate 227 of 364 days2008: Unhealthy for Sensitive Groups 4 of 364 days2009: Good 119 of 365 days2009: Moderate 242 of 365 days2009: Unhealthy for Sensitive Groups 4 of 365 days2010: Good 69 of 365 days2010: Moderate 286 of 365 days2010: Unhealthy for Sensitive Groups 10 of 365 days20102011: Good 85 of 365 days2011: Moderate 280 of 365 days2012: Good 70 of 366 days2012: Moderate 285 of 366 days2012: Unhealthy for Sensitive Groups 11 of 366 days2013: Good 81 of 365 days2013: Moderate 281 of 365 days2013: Unhealthy for Sensitive Groups 3 of 365 days2014: Good 109 of 365 days2014: Moderate 252 of 365 days2014: Unhealthy for Sensitive Groups 4 of 365 days2015: Good 114 of 365 days2015: Moderate 250 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days20152016: Good 92 of 366 days2016: Moderate 273 of 366 days2016: Unhealthy for Sensitive Groups 1 of 366 days2017: Good 57 of 364 days2017: Moderate 307 of 364 days2018: Good 168 of 365 days2018: Moderate 197 of 365 days2019: Good 192 of 364 days2019: Moderate 172 of 364 days2020: Good 199 of 324 days2020: Moderate 125 of 324 days20202021: Good 134 of 365 days2021: Moderate 229 of 365 days2021: Unhealthy for Sensitive Groups 2 of 365 days2022: Good 165 of 364 days2022: Moderate 198 of 364 days2022: Unhealthy for Sensitive Groups 1 of 364 days2023: Good 132 of 365 days2023: Moderate 215 of 365 days2023: Unhealthy for Sensitive Groups 14 of 365 days2023: Unhealthy 3 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 230 of 365 days2024: Moderate 135 of 365 days2025: Good 217 of 365 days2025: Moderate 145 of 365 days2025: Unhealthy for Sensitive Groups 2 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 year0501001985: 90th percentile AQI 401986: 90th percentile AQI 541987: 90th percentile AQI 511988: 90th percentile AQI 591989: 90th percentile AQI 491990: 90th percentile AQI 511991: 90th percentile AQI 501992: 90th percentile AQI 511993: 90th percentile AQI 431994: 90th percentile AQI 491995: 90th percentile AQI 531996: 90th percentile AQI 441997: 90th percentile AQI 471998: 90th percentile AQI 401999: 90th percentile AQI 862000: 90th percentile AQI 742001: 90th percentile AQI 762002: 90th percentile AQI 742003: 90th percentile AQI 802004: 90th percentile AQI 642005: 90th percentile AQI 822006: 90th percentile AQI 732007: 90th percentile AQI 812008: 90th percentile AQI 752009: 90th percentile AQI 782010: 90th percentile AQI 822011: 90th percentile AQI 772012: 90th percentile AQI 802013: 90th percentile AQI 742014: 90th percentile AQI 742015: 90th percentile AQI 732016: 90th percentile AQI 712017: 90th percentile AQI 722018: 90th percentile AQI 682019: 90th percentile AQI 652020: 90th percentile AQI 622021: 90th percentile AQI 702022: 90th percentile AQI 672023: 90th percentile AQI 802024: 90th percentile AQI 592025: 90th percentile AQI 711985: Median AQI 171986: Median AQI 311987: Median AQI 291988: Median AQI 311989: Median AQI 261990: Median AQI 261991: Median AQI 261992: Median AQI 271993: Median AQI 241994: Median AQI 271995: Median AQI 301996: Median AQI 231997: Median AQI 261998: Median AQI 201999: Median AQI 412000: Median AQI 412001: Median AQI 392002: Median AQI 362003: Median AQI 402004: Median AQI 362005: Median AQI 432006: Median AQI 472007: Median AQI 552008: Median AQI 552009: Median AQI 562010: Median AQI 592011: Median AQI 602012: Median AQI 602013: Median AQI 582014: Median AQI 562015: Median AQI 562016: Median AQI 572017: Median AQI 582018: Median AQI 522019: Median AQI 492020: Median AQI 452021: Median AQI 552022: Median AQI 522023: Median AQI 542024: Median AQI 462025: Median AQI 45198519901995200020052010201520202025
  • 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)22762%
Ozone13838%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536521714521004571166PM2.5
20243652301350000465990PM2.5
2023365132215143105480235PM2.5
202236416519810005267107PM2.5
202136513422920005570112PM2.5
20203241991250000456287PM2.5
20193641921720000496591PM2.5
201836516819700005268100PM2.5
2017364573070000587293PM2.5
20163669227310005771108PM2.5
201536511425010005673146PM2.5
201436510925240005674124PM2.5
20133658128130005874115PM2.5
201236670285110006080126PM2.5
20113658528000006077100PM2.5
201036569286100005982125PM2.5
200936511924240005678134PM2.5
200836413322740005575138PM2.5
2007358124221130005581136PM2.5
200626214611330004773139Ozone
2005323197107181004382154Ozone
20043612748250003664122Ozone
200336325594140004080133Ozone
200236525297151003674172Ozone
200136225298120003976136Ozone
200035724710550004174150Ozone
1999361232112143004186166Ozone
1998348335130000204074PM10
1997348324240000264763PM10
1996351332190000234465PM10
1995358313450000305368PM10
1994290267230000274982PM10
199317316760000244361PM10
1992146131150000275162PM10
1991178162160000265079PM10
1990177157200000265198PM10
1989172156160000264974PM10
1988178144340000315993PM10
1987182161210000295179PM10
1986171143280000315474PM10
1985262510000174055PM10

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 1985–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem