EnviroNearby

Montgomery County, Iowa air quality history

Daily Air Quality Index summaries from EPA monitors in Montgomery, Iowa, 2002–2025.

69%
Good days in 2025
43
Median daily AQI, 2025
1
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 Montgomery, Iowa on 365 days. 253 of those days (69%) were in the Good range, and the median daily AQI was 43. 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 233 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 67% in 2002–2004 versus 69% 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%2002: Good 82 of 149 days2002: Moderate 62 of 149 days2002: Unhealthy for Sensitive Groups 5 of 149 days20022003: Good 180 of 264 days2003: Moderate 82 of 264 days2003: Unhealthy for Sensitive Groups 2 of 264 days2004: Good 204 of 260 days2004: Moderate 56 of 260 days20042005: Good 225 of 313 days2005: Moderate 86 of 313 days2005: Unhealthy for Sensitive Groups 2 of 313 days2006: Good 200 of 269 days2006: Moderate 67 of 269 days2006: Unhealthy for Sensitive Groups 2 of 269 days20062007: Good 172 of 261 days2007: Moderate 85 of 261 days2007: Unhealthy for Sensitive Groups 4 of 261 days2008: Good 190 of 259 days2008: Moderate 69 of 259 days20082009: Good 205 of 267 days2009: Moderate 60 of 267 days2009: Unhealthy for Sensitive Groups 2 of 267 days2010: Good 164 of 309 days2010: Moderate 143 of 309 days2010: Unhealthy for Sensitive Groups 2 of 309 days20102011: Good 198 of 362 days2011: Moderate 164 of 362 days2012: Good 183 of 365 days2012: Moderate 177 of 365 days2012: Unhealthy for Sensitive Groups 5 of 365 days20122013: Good 187 of 365 days2013: Moderate 174 of 365 days2013: Unhealthy for Sensitive Groups 4 of 365 days2014: Good 196 of 364 days2014: Moderate 167 of 364 days2014: Unhealthy for Sensitive Groups 1 of 364 days20142015: Good 231 of 365 days2015: Moderate 134 of 365 days2016: Good 232 of 366 days2016: Moderate 133 of 366 days2016: Unhealthy for Sensitive Groups 1 of 366 days20162017: Good 228 of 364 days2017: Moderate 136 of 364 days2018: Good 219 of 365 days2018: Moderate 146 of 365 days20182019: Good 267 of 364 days2019: Moderate 97 of 364 days2020: Good 277 of 366 days2020: Moderate 89 of 366 days20202021: Good 250 of 351 days2021: Moderate 100 of 351 days2021: Unhealthy for Sensitive Groups 1 of 351 days2022: Good 305 of 363 days2022: Moderate 58 of 363 days20222023: Good 226 of 364 days2023: Moderate 131 of 364 days2023: Unhealthy for Sensitive Groups 7 of 364 days2024: Good 272 of 354 days2024: Moderate 82 of 354 days20242025: Good 253 of 365 days2025: Moderate 111 of 365 days2025: Unhealthy for Sensitive Groups 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 year0501002002: 90th percentile AQI 872003: 90th percentile AQI 682004: 90th percentile AQI 582005: 90th percentile AQI 642006: 90th percentile AQI 652007: 90th percentile AQI 662008: 90th percentile AQI 582009: 90th percentile AQI 592010: 90th percentile AQI 672011: 90th percentile AQI 662012: 90th percentile AQI 712013: 90th percentile AQI 662014: 90th percentile AQI 632015: 90th percentile AQI 612016: 90th percentile AQI 582017: 90th percentile AQI 602018: 90th percentile AQI 632019: 90th percentile AQI 582020: 90th percentile AQI 572021: 90th percentile AQI 582022: 90th percentile AQI 542023: 90th percentile AQI 702024: 90th percentile AQI 552025: 90th percentile AQI 612002: Median AQI 472003: Median AQI 422004: Median AQI 372005: Median AQI 362006: Median AQI 392007: Median AQI 432008: Median AQI 422009: Median AQI 392010: Median AQI 492011: Median AQI 482012: Median AQI 502013: Median AQI 502014: Median AQI 482015: Median AQI 442016: Median AQI 442017: Median AQI 452018: Median AQI 462019: Median AQI 412020: Median AQI 412021: Median AQI 422022: Median AQI 392023: Median AQI 442024: Median AQI 422025: Median AQI 432002200420062008201020122014201620182020202220242025
  • 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)23364%
Ozone13236%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536525311110004361133PM2.5
2024354272820000425580PM2.5
202336422613170004470147PM2.5
2022363305580000395479PM2.5
202135125010010004258112PM2.5
2020366277890000415779PM2.5
2019364267970000415877PM2.5
20183652191460000466393PM2.5
20173642281360000456084PM2.5
201636623213310004458121PM2.5
20153652311340000446197PM2.5
201436419616710004863107PM2.5
201336518717440005066133PM2.5
201236518317750005071112PM2.5
20113621981640000486693PM2.5
201030916414320004967112PM2.5
20092672056020003959133Ozone
2008259190690000425884Ozone
20072611728540004366108Ozone
20062692006720003965119Ozone
20053132258620003664121Ozone
2004260204560000375894Ozone
20032641808220004268119Ozone
2002149826250004787126Ozone

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 2002–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem