EnviroNearby

Gunnison County, Colorado air quality history

Daily Air Quality Index summaries from EPA monitors in Gunnison, Colorado, 1985–2025.

73%
Good days in 2025
46
Median daily AQI, 2025
1
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Gunnison, Colorado on 364 days. 264 of those days (73%) were in the Good range, and the median daily AQI was 46. 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 364 days. Across the years with fuller monitoring, the share of Good days fell: an average of 83% in 1985–1988 versus 69% in 2023–2025.

Years with fewer than 120 monitored days (1987, 1989) 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 138 of 155 days1985: Moderate 17 of 155 days19851986: Good 140 of 195 days1986: Moderate 55 of 195 days1987: Good 95 of 114 days1987: Moderate 19 of 114 days1988: Good 128 of 145 days1988: Moderate 17 of 145 days1989: Good 47 of 61 days1989: Moderate 14 of 61 days1990: Good 277 of 351 days1990: Moderate 73 of 351 days1990: Unhealthy for Sensitive Groups 1 of 351 days19901991: Good 251 of 350 days1991: Moderate 92 of 350 days1991: Unhealthy for Sensitive Groups 7 of 350 days1992: Good 278 of 349 days1992: Moderate 71 of 349 days1993: Good 279 of 361 days1993: Moderate 82 of 361 days1994: Good 220 of 362 days1994: Moderate 137 of 362 days1994: Unhealthy for Sensitive Groups 5 of 362 days1995: Good 240 of 339 days1995: Moderate 98 of 339 days1995: Unhealthy for Sensitive Groups 1 of 339 days19951996: Good 217 of 359 days1996: Moderate 131 of 359 days1996: Unhealthy for Sensitive Groups 11 of 359 days1997: Good 196 of 361 days1997: Moderate 155 of 361 days1997: Unhealthy for Sensitive Groups 10 of 361 days1998: Good 182 of 364 days1998: Moderate 176 of 364 days1998: Unhealthy for Sensitive Groups 6 of 364 days1999: Good 206 of 365 days1999: Moderate 143 of 365 days1999: Unhealthy for Sensitive Groups 16 of 365 days2000: Good 201 of 365 days2000: Moderate 157 of 365 days2000: Unhealthy for Sensitive Groups 7 of 365 days20002001: Good 227 of 365 days2001: Moderate 136 of 365 days2001: Unhealthy for Sensitive Groups 2 of 365 days2002: Good 180 of 363 days2002: Moderate 178 of 363 days2002: Unhealthy for Sensitive Groups 5 of 363 days2003: Good 210 of 364 days2003: Moderate 148 of 364 days2003: Unhealthy for Sensitive Groups 6 of 364 days2004: Good 235 of 366 days2004: Moderate 129 of 366 days2004: Unhealthy for Sensitive Groups 2 of 366 days2005: Good 205 of 363 days2005: Moderate 154 of 363 days2005: Unhealthy for Sensitive Groups 4 of 363 days20052006: Good 225 of 365 days2006: Moderate 138 of 365 days2006: Unhealthy for Sensitive Groups 1 of 365 days2006: Unhealthy 1 of 365 days2007: Good 239 of 365 days2007: Moderate 125 of 365 days2007: Unhealthy for Sensitive Groups 1 of 365 days2008: Good 283 of 361 days2008: Moderate 78 of 361 days2009: Good 284 of 364 days2009: Moderate 78 of 364 days2009: Unhealthy for Sensitive Groups 2 of 364 days2010: Good 308 of 365 days2010: Moderate 55 of 365 days2010: Unhealthy for Sensitive Groups 2 of 365 days20102011: Good 289 of 365 days2011: Moderate 70 of 365 days2011: Unhealthy for Sensitive Groups 6 of 365 days2012: Good 254 of 366 days2012: Moderate 107 of 366 days2012: Unhealthy for Sensitive Groups 5 of 366 days2013: Good 266 of 364 days2013: Moderate 97 of 364 days2013: Unhealthy for Sensitive Groups 1 of 364 days2014: Good 307 of 365 days2014: Moderate 58 of 365 days2015: Good 283 of 365 days2015: Moderate 79 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days20152016: Good 316 of 366 days2016: Moderate 50 of 366 days2017: Good 275 of 363 days2017: Moderate 87 of 363 days2017: Unhealthy for Sensitive Groups 1 of 363 days2018: Good 235 of 365 days2018: Moderate 125 of 365 days2018: Unhealthy for Sensitive Groups 4 of 365 days2018: Unhealthy 1 of 365 days2019: Good 264 of 362 days2019: Moderate 96 of 362 days2019: Unhealthy for Sensitive Groups 2 of 362 days2020: Good 270 of 335 days2020: Moderate 62 of 335 days2020: Unhealthy for Sensitive Groups 3 of 335 days20202021: Good 262 of 365 days2021: Moderate 102 of 365 days2021: Unhealthy for Sensitive Groups 1 of 365 days2022: Good 281 of 365 days2022: Moderate 82 of 365 days2022: Unhealthy for Sensitive Groups 2 of 365 days2023: Good 251 of 363 days2023: Moderate 112 of 363 days2024: Good 243 of 366 days2024: Moderate 123 of 366 days2025: Good 264 of 364 days2025: Moderate 99 of 364 days2025: Unhealthy for Sensitive Groups 1 of 364 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 year0501001985: 90th percentile AQI 521986: 90th percentile AQI 651987: 90th percentile AQI 551988: 90th percentile AQI 551989: 90th percentile AQI 601990: 90th percentile AQI 611991: 90th percentile AQI 711992: 90th percentile AQI 581993: 90th percentile AQI 611994: 90th percentile AQI 711995: 90th percentile AQI 641996: 90th percentile AQI 771997: 90th percentile AQI 771998: 90th percentile AQI 801999: 90th percentile AQI 872000: 90th percentile AQI 772001: 90th percentile AQI 712002: 90th percentile AQI 842003: 90th percentile AQI 742004: 90th percentile AQI 662005: 90th percentile AQI 772006: 90th percentile AQI 742007: 90th percentile AQI 682008: 90th percentile AQI 612009: 90th percentile AQI 612010: 90th percentile AQI 572011: 90th percentile AQI 642012: 90th percentile AQI 642013: 90th percentile AQI 642014: 90th percentile AQI 582015: 90th percentile AQI 612016: 90th percentile AQI 542017: 90th percentile AQI 642018: 90th percentile AQI 772019: 90th percentile AQI 672020: 90th percentile AQI 582021: 90th percentile AQI 712022: 90th percentile AQI 642023: 90th percentile AQI 672024: 90th percentile AQI 672025: 90th percentile AQI 671985: Median AQI 341986: Median AQI 331987: Median AQI 291988: Median AQI 221989: Median AQI 311990: Median AQI 441991: Median AQI 451992: Median AQI 451993: Median AQI 451994: Median AQI 481995: Median AQI 461996: Median AQI 481997: Median AQI 491998: Median AQI 511999: Median AQI 492000: Median AQI 492001: Median AQI 492002: Median AQI 512003: Median AQI 492004: Median AQI 482005: Median AQI 482006: Median AQI 482007: Median AQI 472008: Median AQI 442009: Median AQI 452010: Median AQI 422011: Median AQI 442012: Median AQI 462013: Median AQI 452014: Median AQI 442015: Median AQI 442016: Median AQI 442017: Median AQI 452018: Median AQI 472019: Median AQI 462020: Median AQI 442021: Median AQI 462022: Median AQI 462023: Median AQI 462024: Median AQI 472025: Median AQI 46198519901995200020052010201520202025
  • 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
Ozone364100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253642649910004667115Ozone
202436624312300004767100Ozone
20233632511120000466793Ozone
20223652818220004664108Ozone
202136526210210004671101Ozone
20203352706230004458115Ozone
20193622649620004667101Ozone
201836523512541004777156Ozone
20173632758710004564140Ozone
2016366316500000445487Ozone
20153652837930004461101Ozone
2014365307580000445890Ozone
20133642669710004564117Ozone
201236625410750004664136Ozone
20113652897060004464119Ozone
20103653085520004257129Ozone
20093642847820004561112Ozone
20083612837800004461100Ozone
200736523912510004768103Ozone
200636522513811004874154Ozone
200536320515440004877109Ozone
200436623512920004866112Ozone
200336421014860004974115Ozone
200236318017850005184112Ozone
200136522713620004971115Ozone
200036520115770004977122Ozone
1999365206143160004987143Ozone
199836418217660005180127Ozone
1997361196155100004977137Ozone
1996359217131110004877147Ozone
19953392409810004664101Ozone
199436222013750004871115Ozone
1993361279820000456190Ozone
19923492787100004558100Ozone
19913502519270004571108Ozone
19903512777310004461105Ozone
19896147140000316079PM10
1988145128170000225584PM10
198711495190000295577PM10
1986195140550000336587PM10
1985155138170000345286PM10

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 1985–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem