EnviroNearby

Cerro Gordo County, Iowa air quality history

Daily Air Quality Index summaries from EPA monitors in Cerro Gordo, Iowa, 1985–2023.

98%
Good days in 2021
19
Median daily AQI, 2021
0
Days above 100 in 2021
120
Days with an AQI in 2021 (of 365)

In 2021, EPA reported a daily Air Quality Index (AQI) for Cerro Gordo, Iowa on 120 days. 118 of those days (98%) were in the Good range, and the median daily AQI was 19. That median is lower than the typical monitored county in Iowa (median 44.5 across 14 counties), and lower than the typical monitored U.S. county (41). The main pollutant was coarse particles (PM10) on 120 days. Across the years with fuller monitoring, the share of Good days rose: an average of 81% in 1986–1988 versus 99% in 2017–2021.

EPA did not report an AQI for every day of 2021 here (120 of 365 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 2023; EPA's files for 2024–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1985, 2018, 2019, 2022, 2023) 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 141 of 166 days1986: Moderate 25 of 166 days1987: Good 126 of 155 days1987: Moderate 29 of 155 days1988: Good 133 of 170 days1988: Moderate 36 of 170 days1988: Unhealthy for Sensitive Groups 1 of 170 days1989: Good 119 of 161 days1989: Moderate 42 of 161 days1990: Good 146 of 173 days1990: Moderate 25 of 173 days1990: Unhealthy for Sensitive Groups 1 of 173 days1990: Unhealthy 1 of 173 days19901991: Good 141 of 170 days1991: Moderate 29 of 170 days1992: Good 138 of 176 days1992: Moderate 36 of 176 days1992: Unhealthy for Sensitive Groups 2 of 176 days1993: Good 284 of 348 days1993: Moderate 61 of 348 days1993: Unhealthy for Sensitive Groups 3 of 348 days1994: Good 283 of 339 days1994: Moderate 55 of 339 days1994: Unhealthy for Sensitive Groups 1 of 339 days1995: Good 290 of 340 days1995: Moderate 49 of 340 days1995: Unhealthy for Sensitive Groups 1 of 340 days19951996: Good 300 of 352 days1996: Moderate 51 of 352 days1996: Unhealthy 1 of 352 days1997: Good 312 of 360 days1997: Moderate 48 of 360 days1998: Good 300 of 350 days1998: Moderate 50 of 350 days1999: Good 260 of 355 days1999: Moderate 94 of 355 days1999: Unhealthy 1 of 355 days2000: Good 263 of 358 days2000: Moderate 94 of 358 days2000: Unhealthy for Sensitive Groups 1 of 358 days20002001: Good 255 of 364 days2001: Moderate 109 of 364 days2002: Good 280 of 360 days2002: Moderate 79 of 360 days2002: Unhealthy for Sensitive Groups 1 of 360 days2003: Good 243 of 363 days2003: Moderate 120 of 363 days2004: Good 260 of 362 days2004: Moderate 100 of 362 days2004: Unhealthy for Sensitive Groups 2 of 362 days2005: Good 308 of 365 days2005: Moderate 56 of 365 days2005: Unhealthy for Sensitive Groups 1 of 365 days20052006: Good 315 of 365 days2006: Moderate 50 of 365 days2007: Good 313 of 365 days2007: Moderate 50 of 365 days2007: Unhealthy for Sensitive Groups 2 of 365 days2008: Good 324 of 366 days2008: Moderate 42 of 366 days2009: Good 341 of 365 days2009: Moderate 24 of 365 days2010: Good 346 of 362 days2010: Moderate 16 of 362 days20102011: Good 347 of 358 days2011: Moderate 11 of 358 days2012: Good 344 of 356 days2012: Moderate 12 of 356 days2013: Good 332 of 334 days2013: Moderate 2 of 334 days2014: Good 346 of 348 days2014: Moderate 2 of 348 days2015: Good 352 of 357 days2015: Moderate 5 of 357 days20152016: Good 346 of 350 days2016: Moderate 4 of 350 days2017: Good 231 of 233 days2017: Moderate 2 of 233 days2018: Good 115 of 115 days2019: Good 118 of 118 days2020: Good 120 of 122 days2020: Moderate 2 of 122 days20202021: Good 118 of 120 days2021: Moderate 2 of 120 days2022: Good 116 of 117 days2022: Moderate 1 of 117 days2023: Good 58 of 60 days2023: Moderate 2 of 60 days2023
  • 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 321986: 90th percentile AQI 551987: 90th percentile AQI 561988: 90th percentile AQI 631989: 90th percentile AQI 621990: 90th percentile AQI 541991: 90th percentile AQI 591992: 90th percentile AQI 631993: 90th percentile AQI 581994: 90th percentile AQI 571995: 90th percentile AQI 531996: 90th percentile AQI 551997: 90th percentile AQI 531998: 90th percentile AQI 531999: 90th percentile AQI 632000: 90th percentile AQI 662001: 90th percentile AQI 642002: 90th percentile AQI 602003: 90th percentile AQI 662004: 90th percentile AQI 642005: 90th percentile AQI 542006: 90th percentile AQI 542007: 90th percentile AQI 552008: 90th percentile AQI 532009: 90th percentile AQI 462010: 90th percentile AQI 382011: 90th percentile AQI 342012: 90th percentile AQI 392013: 90th percentile AQI 332014: 90th percentile AQI 312015: 90th percentile AQI 332016: 90th percentile AQI 312017: 90th percentile AQI 312018: 90th percentile AQI 312019: 90th percentile AQI 272020: 90th percentile AQI 372021: 90th percentile AQI 312022: 90th percentile AQI 312023: 90th percentile AQI 411985: Median AQI 181986: Median AQI 311987: Median AQI 301988: Median AQI 331989: Median AQI 341990: Median AQI 301991: Median AQI 291992: Median AQI 341993: Median AQI 311994: Median AQI 311995: Median AQI 311996: Median AQI 291997: Median AQI 291998: Median AQI 301999: Median AQI 322000: Median AQI 332001: Median AQI 362002: Median AQI 322003: Median AQI 402004: Median AQI 332005: Median AQI 292006: Median AQI 282007: Median AQI 312008: Median AQI 262009: Median AQI 232010: Median AQI 182011: Median AQI 192012: Median AQI 192013: Median AQI 182014: Median AQI 162015: Median AQI 162016: Median AQI 152017: Median AQI 152018: Median AQI 162019: Median AQI 152020: Median AQI 182021: Median AQI 192022: Median AQI 172023: Median AQI 19198519901995200020052010201520202023
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2021

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
Coarse particles (PM10)120100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2023605820000194156PM10
202211711610000173161PM10
202112011820000193156PM10
202012212020000183760PM10
201911811800000152738PM10
201811511500000163146PM10
201723323120000153165PM10
201635034640000153159PM10
201535735250000163358PM10
201434834620000163152PM10
201333433220000183360PM10
2012356344120000193966PM10
2011358347110000193462PM10
2010362346160000183864PM10
2009365341240000234672PM10
2008366324420000265375PM10
20073653135020003155104PM10
2006365315500000285495PM10
20053653085610002954105PM10
200436226010020003364118PM10
20033632431200000406693PM10
20023602807910003260107PM10
20013642551090000366497PM10
20003582639410003366116PM10
19993552609401003263159PM10
1998350300500000305386PM10
1997360312480000295381PM10
19963523005101002955166PM10
19953402904910003153142PM10
19943392835510003157103PM10
19933482846130003158112PM10
19921761383620003463118PM10
1991170141290000295975PM10
19901731462511003054161PM10
1989161119420000346284PM10
19881701333610003363110PM10
1987155126290000305685PM10
1986166141250000315584PM10
1985262510000183254PM10

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.

All monitored counties in Iowa

Source: U.S. EPA AirData, “Annual AQI by County” files for 1985–2023 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem