EnviroNearby

Routt County, Colorado air quality history

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

94%
Good days in 2025
22
Median daily AQI, 2025
0
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 Routt, Colorado on 365 days. 342 of those days (94%) were in the Good range, and the median daily AQI was 22. 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 341 days. Across the years with fuller monitoring, the share of Good days rose: an average of 80% in 1985–1988 versus 97% in 2023–2025.

Years with fewer than 120 monitored days (1987) 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 99 of 123 days1985: Moderate 24 of 123 days19851986: Good 187 of 238 days1986: Moderate 51 of 238 days1987: Good 101 of 118 days1987: Moderate 17 of 118 days1988: Good 141 of 173 days1988: Moderate 32 of 173 days1989: Good 136 of 163 days1989: Moderate 26 of 163 days1989: Unhealthy for Sensitive Groups 1 of 163 days1990: Good 142 of 173 days1990: Moderate 29 of 173 days1990: Unhealthy for Sensitive Groups 2 of 173 days19901991: Good 135 of 182 days1991: Moderate 46 of 182 days1991: Unhealthy for Sensitive Groups 1 of 182 days1992: Good 279 of 324 days1992: Moderate 45 of 324 days1993: Good 309 of 355 days1993: Moderate 45 of 355 days1993: Unhealthy for Sensitive Groups 1 of 355 days1994: Good 303 of 356 days1994: Moderate 52 of 356 days1994: Unhealthy for Sensitive Groups 1 of 356 days1995: Good 300 of 350 days1995: Moderate 50 of 350 days19951996: Good 283 of 325 days1996: Moderate 41 of 325 days1996: Unhealthy for Sensitive Groups 1 of 325 days1997: Good 318 of 352 days1997: Moderate 34 of 352 days1998: Good 330 of 352 days1998: Moderate 22 of 352 days1999: Good 287 of 319 days1999: Moderate 32 of 319 days2000: Good 306 of 337 days2000: Moderate 31 of 337 days20002001: Good 321 of 351 days2001: Moderate 30 of 351 days2002: Good 315 of 348 days2002: Moderate 33 of 348 days2003: Good 323 of 351 days2003: Moderate 28 of 351 days2004: Good 304 of 334 days2004: Moderate 30 of 334 days2005: Good 310 of 329 days2005: Moderate 19 of 329 days20052006: Good 331 of 352 days2006: Moderate 21 of 352 days2007: Good 340 of 357 days2007: Moderate 17 of 357 days2008: Good 276 of 298 days2008: Moderate 22 of 298 days2009: Good 331 of 350 days2009: Moderate 19 of 350 days2010: Good 331 of 351 days2010: Moderate 20 of 351 days20102011: Good 331 of 343 days2011: Moderate 12 of 343 days2012: Good 346 of 353 days2012: Moderate 7 of 353 days2013: Good 336 of 349 days2013: Moderate 13 of 349 days2014: Good 334 of 346 days2014: Moderate 12 of 346 days2015: Good 357 of 364 days2015: Moderate 7 of 364 days20152016: Good 343 of 352 days2016: Moderate 9 of 352 days2017: Good 333 of 342 days2017: Moderate 9 of 342 days2018: Good 354 of 355 days2018: Moderate 1 of 355 days2019: Good 353 of 356 days2019: Moderate 2 of 356 days2019: Unhealthy for Sensitive Groups 1 of 356 days2020: Good 353 of 358 days2020: Moderate 5 of 358 days20202021: Good 347 of 354 days2021: Moderate 7 of 354 days2022: Good 356 of 356 days2023: Good 348 of 353 days2023: Moderate 5 of 353 days2024: Good 364 of 365 days2024: Moderate 1 of 365 days2025: Good 342 of 365 days2025: Moderate 23 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 year0501001985: 90th percentile AQI 551986: 90th percentile AQI 671987: 90th percentile AQI 601988: 90th percentile AQI 581989: 90th percentile AQI 571990: 90th percentile AQI 581991: 90th percentile AQI 701992: 90th percentile AQI 571993: 90th percentile AQI 571994: 90th percentile AQI 571995: 90th percentile AQI 571996: 90th percentile AQI 551997: 90th percentile AQI 491998: 90th percentile AQI 431999: 90th percentile AQI 512000: 90th percentile AQI 462001: 90th percentile AQI 462002: 90th percentile AQI 482003: 90th percentile AQI 452004: 90th percentile AQI 492005: 90th percentile AQI 392006: 90th percentile AQI 392007: 90th percentile AQI 362008: 90th percentile AQI 452009: 90th percentile AQI 462010: 90th percentile AQI 372011: 90th percentile AQI 322012: 90th percentile AQI 322013: 90th percentile AQI 312014: 90th percentile AQI 352015: 90th percentile AQI 322016: 90th percentile AQI 262017: 90th percentile AQI 312018: 90th percentile AQI 302019: 90th percentile AQI 272020: 90th percentile AQI 292021: 90th percentile AQI 312022: 90th percentile AQI 252023: 90th percentile AQI 232024: 90th percentile AQI 252025: 90th percentile AQI 421985: Median AQI 341986: Median AQI 301987: Median AQI 251988: Median AQI 221989: Median AQI 251990: Median AQI 261991: Median AQI 271992: Median AQI 241993: Median AQI 251994: Median AQI 221995: Median AQI 201996: Median AQI 231997: Median AQI 201998: Median AQI 201999: Median AQI 182000: Median AQI 202001: Median AQI 192002: Median AQI 202003: Median AQI 202004: Median AQI 182005: Median AQI 172006: Median AQI 192007: Median AQI 192008: Median AQI 212009: Median AQI 172010: Median AQI 162011: Median AQI 152012: Median AQI 152013: Median AQI 152014: Median AQI 152015: Median AQI 132016: Median AQI 152017: Median AQI 152018: Median AQI 152019: Median AQI 132020: Median AQI 142021: Median AQI 152022: Median AQI 132023: Median AQI 132024: Median AQI 122025: Median AQI 22198519901995200020052010201520202025
  • 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)34193%
Coarse particles (PM10)247%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365342230000224287PM2.5
202436536410000122553PM10
202335334850000132358PM10
202235635600000132543PM10
202135434770000153168PM10
202035835350000142968PM10
2019356353210001327137PM10
201835535410000153051PM10
201734233390000153162PM10
201635234390000152660PM10
201536435770000133258PM10
2014346334120000153565PM10
2013349336130000153164PM10
201235334670000153285PM10
2011343331120000153291PM10
2010351331200000163773PM10
2009350331190000174665PM10
2008298276220000214585PM10
2007357340170000193673PM10
2006352331210000193967PM10
2005329310190000173966PM10
2004334304300000184986PM10
2003351323280000204598PM10
2002348315330000204883PM10
2001351321300000194673PM10
2000337306310000204672PM10
1999319287320000185197PM10
1998352330220000204364PM10
1997352318340000204982PM10
19963252834110002355102PM10
1995350300500000205793PM10
19943563035210002257121PM10
19933553094510002557102PM10
1992324279450000245784PM10
19911821354610002770109PM10
19901731422920002658105PM10
19891631362610002557105PM10
1988173141320000225886PM10
1987118101170000256088PM10
1986238187510000306796PM10
198512399240000345567PM10

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