EnviroNearby

Chaffee County, Colorado air quality history

Daily Air Quality Index summaries from EPA monitors in Chaffee, Colorado, 2009–2025.

46%
Good days in 2024
51
Median daily AQI, 2024
5
Days above 100 in 2024
161
Days with an AQI in 2024 (of 366)

In 2024, EPA reported a daily Air Quality Index (AQI) for Chaffee, Colorado on 161 days. 74 of those days (46%) were in the Good range, and the median daily AQI was 51. That median is higher than the typical monitored county in Colorado (median 47.5 across 30 counties), and higher than the typical monitored U.S. county (41). The main pollutant was ozone on 161 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 50% in 2010–2013 versus 50% in 2022–2024.

EPA did not report an AQI for every day of 2024 here (161 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.

Years with fewer than 120 monitored days (2009, 2012, 2015, 2020, 2021, 2025) 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%2009: Good 66 of 106 days2009: Moderate 40 of 106 days20092010: Good 70 of 128 days2010: Moderate 55 of 128 days2010: Unhealthy for Sensitive Groups 3 of 128 days2011: Good 83 of 153 days2011: Moderate 64 of 153 days2011: Unhealthy for Sensitive Groups 6 of 153 days20112012: Good 33 of 69 days2012: Moderate 34 of 69 days2012: Unhealthy for Sensitive Groups 2 of 69 days2013: Good 59 of 145 days2013: Moderate 82 of 145 days2013: Unhealthy for Sensitive Groups 4 of 145 days20132014: Good 103 of 150 days2014: Moderate 47 of 150 days2015: Good 65 of 100 days2015: Moderate 34 of 100 days2015: Unhealthy for Sensitive Groups 1 of 100 days20152016: Good 97 of 151 days2016: Moderate 51 of 151 days2016: Unhealthy for Sensitive Groups 3 of 151 days2017: Good 144 of 144 days20172018: Good 67 of 164 days2018: Moderate 91 of 164 days2018: Unhealthy for Sensitive Groups 5 of 164 days2018: Unhealthy 1 of 164 days2019: Good 80 of 144 days2019: Moderate 63 of 144 days2019: Unhealthy for Sensitive Groups 1 of 144 days20192020: Good 37 of 69 days2020: Moderate 29 of 69 days2020: Unhealthy for Sensitive Groups 3 of 69 days2021: Good 47 of 112 days2021: Moderate 59 of 112 days2021: Unhealthy for Sensitive Groups 6 of 112 days20212022: Good 98 of 156 days2022: Moderate 57 of 156 days2022: Unhealthy for Sensitive Groups 1 of 156 days2023: Good 66 of 166 days2023: Moderate 96 of 166 days2023: Unhealthy for Sensitive Groups 4 of 166 days20232024: Good 74 of 161 days2024: Moderate 82 of 161 days2024: Unhealthy for Sensitive Groups 5 of 161 days2025: Good 68 of 103 days2025: Moderate 30 of 103 days2025: Unhealthy for Sensitive Groups 5 of 103 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 year0501002009: 90th percentile AQI 712010: 90th percentile AQI 772011: 90th percentile AQI 872012: 90th percentile AQI 872013: 90th percentile AQI 872014: 90th percentile AQI 772015: 90th percentile AQI 642016: 90th percentile AQI 712017: 90th percentile AQI 402018: 90th percentile AQI 872019: 90th percentile AQI 772020: 90th percentile AQI 842021: 90th percentile AQI 932022: 90th percentile AQI 672023: 90th percentile AQI 872024: 90th percentile AQI 842025: 90th percentile AQI 842009: Median AQI 492010: Median AQI 502011: Median AQI 502012: Median AQI 542013: Median AQI 542014: Median AQI 472015: Median AQI 472016: Median AQI 472017: Median AQI 352018: Median AQI 582019: Median AQI 502020: Median AQI 502021: Median AQI 582022: Median AQI 492023: Median AQI 582024: Median AQI 512025: Median AQI 48200920112013201520172019202120232025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2024

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
Ozone161100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025103683050004884108Ozone
2024161748250005184112Ozone
2023166669640005887115Ozone
2022156985710004967119Ozone
2021112475960005893119Ozone
202069372930005084101Ozone
2019144806310005077108Ozone
2018164679151005887161Ozone
201714414400000354044Ozone
2016151975130004771105Ozone
2015100653410004764108Ozone
20141501034700004777100Ozone
2013145598240005487126Ozone
201269333420005487108Ozone
2011153836460005087112Ozone
2010128705530005077101Ozone
2009106664000004971100Ozone

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 Colorado with a similar median AQI in 2024

All monitored counties in Colorado

Source: U.S. EPA AirData, “Annual AQI by County” files for 2009–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem