EnviroNearby

Clear Creek County, Colorado air quality history

Daily Air Quality Index summaries from EPA monitors in Clear Creek, Colorado, 2007–2025.

68%
Good days in 2025
48
Median daily AQI, 2025
0
Days above 100 in 2025
315
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Clear Creek, Colorado on 315 days. 214 of those days (68%) were in the Good range, and the median daily AQI was 48. That median is about the same as the typical monitored county in Colorado (median 46 across 27 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 315 days. Across the years with fuller monitoring, the share of Good days rose: an average of 36% in 2011–2014 versus 61% in 2023–2025.

Years with fewer than 120 monitored days (2007, 2008, 2009, 2010, 2012) 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%2007: Good 13 of 85 days2007: Moderate 29 of 85 days2007: Unhealthy for Sensitive Groups 29 of 85 days2007: Unhealthy 13 of 85 days2007: Very Unhealthy 1 of 85 days20072008: Good 27 of 105 days2008: Moderate 65 of 105 days2008: Unhealthy for Sensitive Groups 12 of 105 days2008: Unhealthy 1 of 105 days2009: Good 38 of 70 days2009: Moderate 32 of 70 days20092010: Good 4 of 105 days2010: Moderate 78 of 105 days2010: Unhealthy for Sensitive Groups 21 of 105 days2010: Unhealthy 2 of 105 days2011: Good 31 of 126 days2011: Moderate 72 of 126 days2011: Unhealthy for Sensitive Groups 21 of 126 days2011: Unhealthy 2 of 126 days20112012: Good 9 of 104 days2012: Moderate 58 of 104 days2012: Unhealthy for Sensitive Groups 35 of 104 days2012: Unhealthy 2 of 104 days2013: Good 26 of 122 days2013: Moderate 78 of 122 days2013: Unhealthy for Sensitive Groups 15 of 122 days2013: Unhealthy 3 of 122 days20132014: Good 169 of 267 days2014: Moderate 83 of 267 days2014: Unhealthy for Sensitive Groups 15 of 267 days2015: Good 182 of 295 days2015: Moderate 107 of 295 days2015: Unhealthy for Sensitive Groups 6 of 295 days20152016: Good 210 of 311 days2016: Moderate 94 of 311 days2016: Unhealthy for Sensitive Groups 6 of 311 days2016: Unhealthy 1 of 311 days2017: Good 173 of 314 days2017: Moderate 137 of 314 days2017: Unhealthy for Sensitive Groups 4 of 314 days20172018: Good 145 of 291 days2018: Moderate 118 of 291 days2018: Unhealthy for Sensitive Groups 25 of 291 days2018: Unhealthy 3 of 291 days2019: Good 183 of 294 days2019: Moderate 109 of 294 days2019: Unhealthy for Sensitive Groups 2 of 294 days20192020: Good 140 of 239 days2020: Moderate 87 of 239 days2020: Unhealthy for Sensitive Groups 10 of 239 days2020: Unhealthy 2 of 239 days2021: Good 206 of 357 days2021: Moderate 127 of 357 days2021: Unhealthy for Sensitive Groups 22 of 357 days2021: Unhealthy 2 of 357 days20212022: Good 244 of 359 days2022: Moderate 110 of 359 days2022: Unhealthy for Sensitive Groups 5 of 359 days2023: Good 204 of 359 days2023: Moderate 147 of 359 days2023: Unhealthy for Sensitive Groups 8 of 359 days20232024: Good 202 of 351 days2024: Moderate 139 of 351 days2024: Unhealthy for Sensitive Groups 10 of 351 days2025: Good 214 of 315 days2025: Moderate 101 of 315 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 year0501001502002007: 90th percentile AQI 1642008: 90th percentile AQI 1052009: 90th percentile AQI 802010: 90th percentile AQI 1152011: 90th percentile AQI 1152012: 90th percentile AQI 1222013: 90th percentile AQI 1052014: 90th percentile AQI 902015: 90th percentile AQI 742016: 90th percentile AQI 772017: 90th percentile AQI 742018: 90th percentile AQI 1002019: 90th percentile AQI 742020: 90th percentile AQI 842021: 90th percentile AQI 932022: 90th percentile AQI 742023: 90th percentile AQI 842024: 90th percentile AQI 802025: 90th percentile AQI 672007: Median AQI 1012008: Median AQI 672009: Median AQI 502010: Median AQI 742011: Median AQI 772012: Median AQI 902013: Median AQI 772014: Median AQI 472015: Median AQI 482016: Median AQI 472017: Median AQI 502018: Median AQI 512019: Median AQI 472020: Median AQI 492021: Median AQI 492022: Median AQI 472023: Median AQI 492024: Median AQI 492025: Median AQI 482007200920112013201520172019202120232025
  • 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
Ozone315100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202531521410100004867100Ozone
2024351202139100004980136Ozone
202335920414780004984136Ozone
202235924411050004774126Ozone
2021357206127222004993154Ozone
202023914087102004984156Ozone
201929418310920004774126Ozone
20182911451182530051100164Ozone
201731417313740005074140Ozone
20163112109461004777154Ozone
201529518210760004874140Ozone
201426716983150004790150Ozone
201312226781530077105156Ozone
20121049583520090122179Ozone
201112631722120077115187Ozone
20101054782120074115161Ozone
20097038320000508097Ozone
200810527651210067105151Ozone
2007851329291310101164201Ozone

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 2025

All monitored counties in Colorado

Source: U.S. EPA AirData, “Annual AQI by County” files for 2007–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem