EnviroNearby

Linn County, Iowa air quality history

Daily Air Quality Index summaries from EPA monitors in Linn, Iowa, 1980–2025.

61%
Good days in 2025
44
Median daily AQI, 2025
5
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 Linn, Iowa on 365 days. 224 of those days (61%) were in the Good range, and the median daily AQI was 44. 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 247 days. Across the years with fuller monitoring, the share of Good days fell: an average of 89% in 1980–1982 versus 54% 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 291 of 341 days1980: Moderate 49 of 341 days1980: Unhealthy for Sensitive Groups 1 of 341 days19801981: Good 324 of 365 days1981: Moderate 37 of 365 days1981: Unhealthy for Sensitive Groups 4 of 365 days1982: Good 340 of 365 days1982: Moderate 25 of 365 days1983: Good 300 of 365 days1983: Moderate 56 of 365 days1983: Unhealthy for Sensitive Groups 6 of 365 days1983: Unhealthy 3 of 365 days1984: Good 284 of 366 days1984: Moderate 79 of 366 days1984: Unhealthy for Sensitive Groups 2 of 366 days1984: Unhealthy 1 of 366 days1985: Good 329 of 365 days1985: Moderate 34 of 365 days1985: Unhealthy for Sensitive Groups 2 of 365 days19851986: Good 321 of 365 days1986: Moderate 43 of 365 days1986: Unhealthy for Sensitive Groups 1 of 365 days1987: Good 302 of 365 days1987: Moderate 60 of 365 days1987: Unhealthy for Sensitive Groups 2 of 365 days1987: Unhealthy 1 of 365 days1988: Good 274 of 366 days1988: Moderate 64 of 366 days1988: Unhealthy for Sensitive Groups 25 of 366 days1988: Unhealthy 3 of 366 days1989: Good 314 of 365 days1989: Moderate 46 of 365 days1989: Unhealthy for Sensitive Groups 4 of 365 days1989: Unhealthy 1 of 365 days1990: Good 353 of 365 days1990: Moderate 12 of 365 days19901991: Good 334 of 365 days1991: Moderate 29 of 365 days1991: Unhealthy for Sensitive Groups 2 of 365 days1992: Good 338 of 366 days1992: Moderate 23 of 366 days1992: Unhealthy for Sensitive Groups 5 of 366 days1993: Good 353 of 365 days1993: Moderate 11 of 365 days1993: Unhealthy for Sensitive Groups 1 of 365 days1994: Good 350 of 365 days1994: Moderate 15 of 365 days1995: Good 341 of 365 days1995: Moderate 24 of 365 days19951996: Good 350 of 366 days1996: Moderate 16 of 366 days1997: Good 333 of 365 days1997: Moderate 31 of 365 days1997: Unhealthy for Sensitive Groups 1 of 365 days1998: Good 327 of 365 days1998: Moderate 37 of 365 days1998: Unhealthy for Sensitive Groups 1 of 365 days1999: Good 252 of 365 days1999: Moderate 97 of 365 days1999: Unhealthy for Sensitive Groups 14 of 365 days1999: Unhealthy 2 of 365 days2000: Good 176 of 366 days2000: Moderate 182 of 366 days2000: Unhealthy for Sensitive Groups 7 of 366 days2000: Unhealthy 1 of 366 days20002001: Good 169 of 365 days2001: Moderate 189 of 365 days2001: Unhealthy for Sensitive Groups 7 of 365 days2002: Good 179 of 365 days2002: Moderate 175 of 365 days2002: Unhealthy for Sensitive Groups 11 of 365 days2003: Good 180 of 365 days2003: Moderate 176 of 365 days2003: Unhealthy for Sensitive Groups 9 of 365 days2004: Good 194 of 366 days2004: Moderate 170 of 366 days2004: Unhealthy for Sensitive Groups 2 of 366 days2005: Good 170 of 365 days2005: Moderate 182 of 365 days2005: Unhealthy for Sensitive Groups 13 of 365 days20052006: Good 275 of 365 days2006: Moderate 89 of 365 days2006: Unhealthy for Sensitive Groups 1 of 365 days2007: Good 264 of 365 days2007: Moderate 94 of 365 days2007: Unhealthy for Sensitive Groups 7 of 365 days2008: Good 147 of 366 days2008: Moderate 217 of 366 days2008: Unhealthy for Sensitive Groups 2 of 366 days2009: Good 166 of 365 days2009: Moderate 195 of 365 days2009: Unhealthy for Sensitive Groups 4 of 365 days2010: Good 145 of 365 days2010: Moderate 214 of 365 days2010: Unhealthy for Sensitive Groups 6 of 365 days20102011: Good 169 of 365 days2011: Moderate 196 of 365 days2012: Good 159 of 366 days2012: Moderate 203 of 366 days2012: Unhealthy for Sensitive Groups 4 of 366 days2013: Good 170 of 365 days2013: Moderate 194 of 365 days2013: Unhealthy for Sensitive Groups 1 of 365 days2014: Good 187 of 365 days2014: Moderate 177 of 365 days2014: Unhealthy for Sensitive Groups 1 of 365 days2015: Good 195 of 365 days2015: Moderate 169 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days20152016: Good 197 of 366 days2016: Moderate 168 of 366 days2016: Unhealthy for Sensitive Groups 1 of 366 days2017: Good 222 of 365 days2017: Moderate 143 of 365 days2018: Good 185 of 365 days2018: Moderate 176 of 365 days2018: Unhealthy for Sensitive Groups 4 of 365 days2019: Good 223 of 365 days2019: Moderate 142 of 365 days2020: Good 207 of 366 days2020: Moderate 158 of 366 days2020: Unhealthy for Sensitive Groups 1 of 366 days20202021: Good 160 of 365 days2021: Moderate 201 of 365 days2021: Unhealthy for Sensitive Groups 4 of 365 days2022: Good 197 of 365 days2022: Moderate 168 of 365 days2023: Good 130 of 365 days2023: Moderate 217 of 365 days2023: Unhealthy for Sensitive Groups 14 of 365 days2023: Unhealthy 3 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 235 of 366 days2024: Moderate 131 of 366 days2025: Good 224 of 365 days2025: Moderate 136 of 365 days2025: Unhealthy for Sensitive Groups 4 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 year0501001980: 90th percentile AQI 571981: 90th percentile AQI 511982: 90th percentile AQI 471983: 90th percentile AQI 641984: 90th percentile AQI 611985: 90th percentile AQI 501986: 90th percentile AQI 521987: 90th percentile AQI 641988: 90th percentile AQI 931989: 90th percentile AQI 551990: 90th percentile AQI 441991: 90th percentile AQI 491992: 90th percentile AQI 481993: 90th percentile AQI 431994: 90th percentile AQI 431995: 90th percentile AQI 441996: 90th percentile AQI 431997: 90th percentile AQI 501998: 90th percentile AQI 511999: 90th percentile AQI 712000: 90th percentile AQI 772001: 90th percentile AQI 802002: 90th percentile AQI 802003: 90th percentile AQI 782004: 90th percentile AQI 702005: 90th percentile AQI 822006: 90th percentile AQI 632007: 90th percentile AQI 742008: 90th percentile AQI 742009: 90th percentile AQI 712010: 90th percentile AQI 752011: 90th percentile AQI 712012: 90th percentile AQI 772013: 90th percentile AQI 662014: 90th percentile AQI 672015: 90th percentile AQI 672016: 90th percentile AQI 632017: 90th percentile AQI 622018: 90th percentile AQI 672019: 90th percentile AQI 642020: 90th percentile AQI 632021: 90th percentile AQI 692022: 90th percentile AQI 612023: 90th percentile AQI 802024: 90th percentile AQI 602025: 90th percentile AQI 681980: Median AQI 311981: Median AQI 311982: Median AQI 311983: Median AQI 351984: Median AQI 391985: Median AQI 341986: Median AQI 341987: Median AQI 341988: Median AQI 361989: Median AQI 341990: Median AQI 291991: Median AQI 311992: Median AQI 281993: Median AQI 301994: Median AQI 301995: Median AQI 291996: Median AQI 271997: Median AQI 311998: Median AQI 321999: Median AQI 382000: Median AQI 512001: Median AQI 522002: Median AQI 512003: Median AQI 512004: Median AQI 472005: Median AQI 522006: Median AQI 382007: Median AQI 382008: Median AQI 542009: Median AQI 522010: Median AQI 532011: Median AQI 522012: Median AQI 522013: Median AQI 522014: Median AQI 502015: Median AQI 482016: Median AQI 472017: Median AQI 452018: Median AQI 502019: Median AQI 432020: Median AQI 472021: Median AQI 522022: Median AQI 482023: Median AQI 542024: Median AQI 442025: Median AQI 441980198519901995200020052010201520202025
  • 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)24768%
Ozone11832%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536522413641004468163PM2.5
20243662351310000446079PM2.5
2023365130217143105480207PM2.5
20223651971680000486181PM2.5
202136516020140005269123PM2.5
202036620715810004763105PM2.5
20193652231420000436486PM2.5
201836518517640005067129PM2.5
20173652221430000456297PM2.5
201636619716810004763106PM2.5
201536519516910004867112PM2.5
201436518717710005067112PM2.5
201336517019410005266122PM2.5
201236615920340005277122PM2.5
201136516919600005271100PM2.5
201036514521460005375113PM2.5
200936516619540005271113PM2.5
200836614721720005474124PM2.5
20073652649470003874147Ozone
20063652758910003863112Ozone
2005365170182130005282133PM2.5
200436619417020004770103PM2.5
200336518017690005178134PM2.5
2002365179175110005180133PM2.5
200136516918970005280136PM2.5
200036617618271005177161PM2.5
199936525297142003871161Ozone
19983653273710003251101Ozone
19973653333110003150112Ozone
1996366350160000274393Ozone
1995365341240000294493Ozone
1994365350150000304393Ozone
19933653531110003043115Ozone
19923663382350002848133Ozone
19913653342920003149108Ozone
1990365353120000294492Ozone
19893653144641003455156Ozone
198836627464253003693161Ozone
19873653026021003464156Ozone
19863653214310003452101Ozone
19853653293420003450105Ozone
19843662847921003961177Ozone
19833653005663003564187Ozone
1982365340250000314790Ozone
19813653243740003151115Ozone
19803412914910003157112Ozone

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 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