EnviroNearby

Story County, Iowa air quality history

Daily Air Quality Index summaries from EPA monitors in Story, Iowa, 1997–2016.

93%
Good days in 2016
35
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 Story, Iowa on 212 days. 198 of those days (93%) were in the Good range, and the median daily AQI was 35. 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 77% in 1997–1999 versus 92% 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 2016; EPA's files for 2017–2025 contain no row for it, which usually means its monitors stopped reporting.

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 185 of 244 days1997: Moderate 50 of 244 days1997: Unhealthy for Sensitive Groups 9 of 244 days19971998: Good 268 of 297 days1998: Moderate 26 of 297 days1998: Unhealthy for Sensitive Groups 3 of 297 days1999: Good 153 of 233 days1999: Moderate 74 of 233 days1999: Unhealthy for Sensitive Groups 6 of 233 days19992000: Good 186 of 257 days2000: Moderate 68 of 257 days2000: Unhealthy for Sensitive Groups 3 of 257 days2001: Good 199 of 257 days2001: Moderate 58 of 257 days20012002: Good 198 of 261 days2002: Moderate 62 of 261 days2002: Unhealthy for Sensitive Groups 1 of 261 days2003: Good 200 of 214 days2003: Moderate 14 of 214 days20032004: Good 200 of 203 days2004: Moderate 3 of 203 days2005: Good 189 of 214 days2005: Moderate 24 of 214 days2005: Unhealthy for Sensitive Groups 1 of 214 days20052006: Good 163 of 184 days2006: Moderate 21 of 184 days2007: Good 176 of 207 days2007: Moderate 27 of 207 days2007: Unhealthy for Sensitive Groups 4 of 207 days20072008: Good 200 of 213 days2008: Moderate 13 of 213 days2009: Good 198 of 214 days2009: Moderate 16 of 214 days20092010: Good 200 of 214 days2010: Moderate 14 of 214 days2011: Good 198 of 214 days2011: Moderate 16 of 214 days20112012: Good 175 of 214 days2012: Moderate 39 of 214 days2013: Good 196 of 214 days2013: Moderate 18 of 214 days20132014: Good 190 of 214 days2014: Moderate 24 of 214 days2015: Good 202 of 213 days2015: Moderate 11 of 213 days20152016: Good 198 of 212 days2016: Moderate 14 of 212 days2016
  • 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 841998: 90th percentile AQI 501999: 90th percentile AQI 742000: 90th percentile AQI 712001: 90th percentile AQI 612002: 90th percentile AQI 642003: 90th percentile AQI 482004: 90th percentile AQI 422005: 90th percentile AQI 512006: 90th percentile AQI 512007: 90th percentile AQI 582008: 90th percentile AQI 482009: 90th percentile AQI 482010: 90th percentile AQI 492011: 90th percentile AQI 492012: 90th percentile AQI 642013: 90th percentile AQI 492014: 90th percentile AQI 512015: 90th percentile AQI 482016: 90th percentile AQI 481997: Median AQI 391998: Median AQI 361999: Median AQI 442000: Median AQI 392001: Median AQI 352002: Median AQI 392003: Median AQI 342004: Median AQI 322005: Median AQI 372006: Median AQI 392007: Median AQI 392008: Median AQI 382009: Median AQI 352010: Median AQI 362011: Median AQI 362012: Median AQI 432013: Median AQI 412014: Median AQI 372015: Median AQI 362016: Median AQI 3519971999200120032005200720092011201320152016
  • 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
2016212198140000354877Ozone
2015213202110000364877Ozone
2014214190240000375190Ozone
2013214196180000414980Ozone
2012214175390000436487Ozone
2011214198160000364987Ozone
2010214200140000364990Ozone
2009214198160000354864Ozone
2008213200130000384871Ozone
20072071762740003958136Ozone
2006184163210000395197Ozone
20052141892410003751105Ozone
200420320030000324267Ozone
20032142001400003448100Ozone
20022611986210003964101Ozone
2001257199580000356190Ozone
20002571866830003971115Ozone
19992331537460004474133Ozone
19982972682630003650108Ozone
19972441855090003984143Ozone

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 1997–2016 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem