EnviroNearby

Warren County, Iowa air quality history

Daily Air Quality Index summaries from EPA monitors in Warren, Iowa, 1997–2017.

96%
Good days in 2016
33
Median daily AQI, 2016
0
Days above 100 in 2016
212
Days with an AQI in 2016 (of 366)

In 2016, EPA reported a daily Air Quality Index (AQI) for Warren, Iowa on 212 days. 203 of those days (96%) were in the Good range, and the median daily AQI was 33. That median is lower than the typical monitored county in Iowa (median 43 across 18 counties), and lower than the typical monitored U.S. county (41). The main pollutant was ozone on 212 days. Across the years with fuller monitoring, the share of Good days rose: an average of 86% in 1997–1999 versus 95% in 2014–2016.

EPA did not report an AQI for every day of 2016 here (212 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 2017; EPA's files for 2018–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2017) 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%1997: Good 244 of 251 days1997: Moderate 7 of 251 days19971998: Good 261 of 292 days1998: Moderate 28 of 292 days1998: Unhealthy for Sensitive Groups 3 of 292 days1999: Good 154 of 213 days1999: Moderate 51 of 213 days1999: Unhealthy for Sensitive Groups 8 of 213 days19992000: Good 153 of 206 days2000: Moderate 48 of 206 days2000: Unhealthy for Sensitive Groups 4 of 206 days2000: Unhealthy 1 of 206 days2001: Good 201 of 212 days2001: Moderate 11 of 212 days20012002: Good 197 of 213 days2002: Moderate 16 of 213 days2003: Good 205 of 214 days2003: Moderate 8 of 214 days2003: Unhealthy for Sensitive Groups 1 of 214 days20032004: Good 170 of 172 days2004: Moderate 2 of 172 days2005: Good 170 of 207 days2005: Moderate 31 of 207 days2005: Unhealthy for Sensitive Groups 6 of 207 days20052006: Good 174 of 205 days2006: Moderate 30 of 205 days2006: Unhealthy for Sensitive Groups 1 of 205 days2007: Good 179 of 204 days2007: Moderate 22 of 204 days2007: Unhealthy for Sensitive Groups 3 of 204 days20072008: Good 199 of 211 days2008: Moderate 12 of 211 days2009: Good 201 of 214 days2009: Moderate 13 of 214 days20092010: Good 187 of 214 days2010: Moderate 27 of 214 days2011: Good 196 of 214 days2011: Moderate 18 of 214 days20112012: Good 160 of 214 days2012: Moderate 52 of 214 days2012: Unhealthy for Sensitive Groups 2 of 214 days2013: Good 192 of 212 days2013: Moderate 20 of 212 days20132014: Good 199 of 213 days2014: Moderate 14 of 213 days2015: Good 204 of 214 days2015: Moderate 10 of 214 days20152016: Good 203 of 212 days2016: Moderate 9 of 212 days2017: Good 91 of 105 days2017: Moderate 14 of 105 days2017
  • 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 441998: 90th percentile AQI 541999: 90th percentile AQI 872000: 90th percentile AQI 802001: 90th percentile AQI 462002: 90th percentile AQI 492003: 90th percentile AQI 472004: 90th percentile AQI 402005: 90th percentile AQI 742006: 90th percentile AQI 542007: 90th percentile AQI 542008: 90th percentile AQI 472009: 90th percentile AQI 482010: 90th percentile AQI 542011: 90th percentile AQI 502012: 90th percentile AQI 742013: 90th percentile AQI 502014: 90th percentile AQI 492015: 90th percentile AQI 462016: 90th percentile AQI 452017: 90th percentile AQI 511997: Median AQI 291998: Median AQI 331999: Median AQI 422000: Median AQI 412001: Median AQI 312002: Median AQI 362003: Median AQI 332004: Median AQI 272005: Median AQI 392006: Median AQI 402007: Median AQI 382008: Median AQI 372009: Median AQI 362010: Median AQI 372011: Median AQI 392012: Median AQI 432013: Median AQI 402014: Median AQI 352015: Median AQI 352016: Median AQI 332017: Median AQI 3919971999200120032005200720092011201320152017
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2016

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
Ozone212100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
201710591140000395167Ozone
201621220390000334571Ozone
2015214204100000354680Ozone
20142131991400003549100Ozone
2013212192200000405077Ozone
20122141605220004374108Ozone
2011214196180000395093Ozone
2010214187270000375487Ozone
2009214201130000364887Ozone
2008211199120000374774Ozone
20072041792230003854119Ozone
20062051743010004054101Ozone
20052071703160003974122Ozone
200417217020000274067Ozone
2003214205810003347108Ozone
2002213197160000364980Ozone
2001212201110000314697Ozone
20002061534841004180151Ozone
19992131545180004287119Ozone
19982922612830003354108Ozone
199725124470000294490Ozone

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 2016

All monitored counties in Iowa

Source: U.S. EPA AirData, “Annual AQI by County” files for 1997–2017 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem