EnviroNearby

Pitkin County, Colorado air quality history

Daily Air Quality Index summaries from EPA monitors in Pitkin, Colorado, 1988–2025.

92%
Good days in 2025
19
Median daily AQI, 2025
1
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Pitkin, Colorado on 365 days. 337 of those days (92%) were in the Good range, and the median daily AQI was 19. That median is lower than the typical monitored county in Colorado (median 46 across 27 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 305 days. Across the years with fuller monitoring, the share of Good days rose: an average of 91% in 1988–1990 versus 96% in 2023–2025.

Years with fewer than 120 monitored days (2014) 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%1988: Good 213 of 231 days1988: Moderate 16 of 231 days1988: Unhealthy for Sensitive Groups 2 of 231 days19881989: Good 288 of 304 days1989: Moderate 16 of 304 days1990: Good 252 of 289 days1990: Moderate 37 of 289 days1991: Good 235 of 284 days1991: Moderate 48 of 284 days1991: Unhealthy for Sensitive Groups 1 of 284 days1992: Good 269 of 302 days1992: Moderate 33 of 302 days1993: Good 331 of 353 days1993: Moderate 22 of 353 days19931994: Good 330 of 343 days1994: Moderate 13 of 343 days1995: Good 329 of 340 days1995: Moderate 11 of 340 days1996: Good 334 of 337 days1996: Moderate 3 of 337 days1997: Good 329 of 338 days1997: Moderate 9 of 338 days1998: Good 358 of 363 days1998: Moderate 5 of 363 days19981999: Good 349 of 363 days1999: Moderate 14 of 363 days2000: Good 300 of 309 days2000: Moderate 9 of 309 days2001: Good 353 of 358 days2001: Moderate 5 of 358 days2002: Good 360 of 364 days2002: Moderate 4 of 364 days2003: Good 360 of 364 days2003: Moderate 4 of 364 days20032004: Good 349 of 350 days2004: Moderate 1 of 350 days2005: Good 353 of 357 days2005: Moderate 4 of 357 days2006: Good 340 of 343 days2006: Moderate 3 of 343 days2007: Good 202 of 361 days2007: Moderate 146 of 361 days2007: Unhealthy for Sensitive Groups 13 of 361 days2008: Good 118 of 121 days2008: Moderate 3 of 121 days20082009: Good 184 of 306 days2009: Moderate 116 of 306 days2009: Unhealthy for Sensitive Groups 5 of 306 days2009: Unhealthy 1 of 306 days2010: Good 214 of 362 days2010: Moderate 142 of 362 days2010: Unhealthy for Sensitive Groups 5 of 362 days2010: Unhealthy 1 of 362 days2011: Good 141 of 363 days2011: Moderate 207 of 363 days2011: Unhealthy for Sensitive Groups 15 of 363 days2012: Good 176 of 182 days2012: Moderate 6 of 182 days2013: Good 235 of 296 days2013: Moderate 61 of 296 days20132014: Good 115 of 115 days2015: Good 121 of 124 days2015: Moderate 3 of 124 days2016: Good 122 of 122 days2017: Good 123 of 123 days2018: Good 120 of 123 days2018: Moderate 3 of 123 days20182019: Good 121 of 121 days2020: Good 116 of 120 days2020: Moderate 4 of 120 days2021: Good 115 of 122 days2021: Moderate 7 of 122 days2022: Good 118 of 122 days2022: Moderate 4 of 122 days2023: Good 120 of 121 days2023: Moderate 1 of 121 days20232024: Good 246 of 257 days2024: Moderate 11 of 257 days2025: Good 337 of 365 days2025: Moderate 27 of 365 days2025: Unhealthy 1 of 365 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 year0501001988: 90th percentile AQI 481989: 90th percentile AQI 421990: 90th percentile AQI 531991: 90th percentile AQI 621992: 90th percentile AQI 521993: 90th percentile AQI 381994: 90th percentile AQI 361995: 90th percentile AQI 381996: 90th percentile AQI 311997: 90th percentile AQI 311998: 90th percentile AQI 311999: 90th percentile AQI 382000: 90th percentile AQI 332001: 90th percentile AQI 352002: 90th percentile AQI 332003: 90th percentile AQI 292004: 90th percentile AQI 272005: 90th percentile AQI 302006: 90th percentile AQI 282007: 90th percentile AQI 872008: 90th percentile AQI 292009: 90th percentile AQI 742010: 90th percentile AQI 772011: 90th percentile AQI 902012: 90th percentile AQI 442013: 90th percentile AQI 642014: 90th percentile AQI 232015: 90th percentile AQI 332016: 90th percentile AQI 242017: 90th percentile AQI 292018: 90th percentile AQI 332019: 90th percentile AQI 192020: 90th percentile AQI 342021: 90th percentile AQI 402022: 90th percentile AQI 282023: 90th percentile AQI 302024: 90th percentile AQI 402025: 90th percentile AQI 431988: Median AQI 251989: Median AQI 241990: Median AQI 241991: Median AQI 211992: Median AQI 211993: Median AQI 191994: Median AQI 191995: Median AQI 181996: Median AQI 171997: Median AQI 171998: Median AQI 191999: Median AQI 222000: Median AQI 182001: Median AQI 192002: Median AQI 182003: Median AQI 172004: Median AQI 162005: Median AQI 162006: Median AQI 162007: Median AQI 442008: Median AQI 162009: Median AQI 492010: Median AQI 492011: Median AQI 542012: Median AQI 312013: Median AQI 442014: Median AQI 122015: Median AQI 122016: Median AQI 122017: Median AQI 142018: Median AQI 152019: Median AQI 112020: Median AQI 122021: Median AQI 142022: Median AQI 142023: Median AQI 132024: Median AQI 192025: Median AQI 19198819931998200320082013201820232025
  • 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
Fine particles (PM2.5)30584%
Coarse particles (PM10)6016%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253653372701001943154PM2.5
2024257246110000194076PM2.5
202312112010000133051PM10
202212211840000142872PM10
202112211570000144090PM10
202012011640000123472PM10
201912112100000111946PM10
201812312030000153353PM10
201712312300000142948PM10
201612212200000122444PM10
201512412130000123360PM10
201411511500000122344PM2.5
2013296235610000446497Ozone
201218217660000314467Ozone
2011363141207150005490119Ozone
201036221414251004977164Ozone
200930618411651004974151Ozone
200812111830000162956PM10
2007361202146130004487126PM10
200634334030000162852PM10
200535735340000163058PM10
200435034910000162756PM10
200336436040000172975PM10
200236436040000183353PM10
200135835350000193570PM10
200030930090000183362PM10
1999363349140000223878PM10
199836335850000193157PM10
199733832990000173169PM10
199633733430000173167PM10
1995340329110000183866PM10
1994343330130000193667PM10
1993353331220000193872PM10
1992302269330000215272PM10
19912842354810002162141PM10
1990289252370000245371PM10
1989304288160000244268PM10
19882312131620002548110PM10

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 1988–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem