EnviroNearby

Sublette County, Wyoming air quality history

Daily Air Quality Index summaries from EPA monitors in Sublette, Wyoming, 1988–2025.

70%
Good days in 2025
47
Median daily AQI, 2025
5
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 Sublette, Wyoming on 365 days. 256 of those days (70%) were in the Good range, and the median daily AQI was 47. That median is higher than the typical monitored county in Wyoming (median 41 across 17 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 350 days. Across the years with fuller monitoring, the share of Good days fell: an average of 80% in 1990–1992 versus 67% in 2023–2025.

Years with fewer than 120 monitored days (1988, 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%1988: Good 70 of 70 days19881989: Good 96 of 96 days1990: Good 300 of 363 days1990: Moderate 63 of 363 days1991: Good 265 of 334 days1991: Moderate 69 of 334 days1992: Good 275 of 354 days1992: Moderate 79 of 354 days1993: Good 283 of 343 days1993: Moderate 60 of 343 days19931994: Good 251 of 359 days1994: Moderate 108 of 359 days1995: Good 209 of 252 days1995: Moderate 43 of 252 days1996: Good 171 of 250 days1996: Moderate 77 of 250 days1996: Unhealthy for Sensitive Groups 2 of 250 days1997: Good 253 of 364 days1997: Moderate 109 of 364 days1997: Unhealthy for Sensitive Groups 2 of 364 days1998: Good 225 of 362 days1998: Moderate 133 of 362 days1998: Unhealthy for Sensitive Groups 4 of 362 days19981999: Good 204 of 361 days1999: Moderate 150 of 361 days1999: Unhealthy for Sensitive Groups 7 of 361 days2000: Good 229 of 362 days2000: Moderate 125 of 362 days2000: Unhealthy for Sensitive Groups 8 of 362 days2001: Good 233 of 358 days2001: Moderate 123 of 358 days2001: Unhealthy for Sensitive Groups 2 of 358 days2002: Good 261 of 361 days2002: Moderate 95 of 361 days2002: Unhealthy for Sensitive Groups 5 of 361 days2003: Good 226 of 307 days2003: Moderate 78 of 307 days2003: Unhealthy for Sensitive Groups 3 of 307 days20032004: Good 284 of 364 days2004: Moderate 80 of 364 days2005: Good 175 of 365 days2005: Moderate 175 of 365 days2005: Unhealthy for Sensitive Groups 12 of 365 days2005: Unhealthy 3 of 365 days2006: Good 149 of 365 days2006: Moderate 204 of 365 days2006: Unhealthy for Sensitive Groups 11 of 365 days2006: Unhealthy 1 of 365 days2007: Good 195 of 365 days2007: Moderate 167 of 365 days2007: Unhealthy for Sensitive Groups 3 of 365 days2008: Good 204 of 366 days2008: Moderate 146 of 366 days2008: Unhealthy for Sensitive Groups 9 of 366 days2008: Unhealthy 6 of 366 days2008: Very Unhealthy 1 of 366 days20082009: Good 268 of 365 days2009: Moderate 97 of 365 days2010: Good 233 of 365 days2010: Moderate 130 of 365 days2010: Unhealthy for Sensitive Groups 2 of 365 days2011: Good 194 of 365 days2011: Moderate 154 of 365 days2011: Unhealthy for Sensitive Groups 12 of 365 days2011: Unhealthy 2 of 365 days2011: Very Unhealthy 3 of 365 days2012: Good 190 of 366 days2012: Moderate 161 of 366 days2012: Unhealthy for Sensitive Groups 9 of 366 days2012: Unhealthy 5 of 366 days2012: Very Unhealthy 1 of 366 days2013: Good 273 of 365 days2013: Moderate 92 of 365 days20132014: Good 272 of 365 days2014: Moderate 93 of 365 days2015: Good 288 of 365 days2015: Moderate 76 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days2016: Good 287 of 366 days2016: Moderate 78 of 366 days2016: Unhealthy for Sensitive Groups 1 of 366 days2017: Good 220 of 365 days2017: Moderate 137 of 365 days2017: Unhealthy for Sensitive Groups 8 of 365 days2018: Good 230 of 365 days2018: Moderate 135 of 365 days20182019: Good 265 of 365 days2019: Moderate 89 of 365 days2019: Unhealthy for Sensitive Groups 8 of 365 days2019: Unhealthy 3 of 365 days2020: Good 289 of 366 days2020: Moderate 72 of 366 days2020: Unhealthy for Sensitive Groups 4 of 366 days2020: Unhealthy 1 of 366 days2021: Good 253 of 365 days2021: Moderate 105 of 365 days2021: Unhealthy for Sensitive Groups 7 of 365 days2022: Good 301 of 365 days2022: Moderate 63 of 365 days2022: Unhealthy for Sensitive Groups 1 of 365 days2023: Good 237 of 365 days2023: Moderate 122 of 365 days2023: Unhealthy for Sensitive Groups 6 of 365 days20232024: Good 244 of 366 days2024: Moderate 115 of 366 days2024: Unhealthy for Sensitive Groups 7 of 366 days2025: Good 256 of 365 days2025: Moderate 104 of 365 days2025: Unhealthy for Sensitive Groups 2 of 365 days2025: Unhealthy 3 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 321989: 90th percentile AQI 271990: 90th percentile AQI 541991: 90th percentile AQI 611992: 90th percentile AQI 641993: 90th percentile AQI 541994: 90th percentile AQI 641995: 90th percentile AQI 581996: 90th percentile AQI 741997: 90th percentile AQI 671998: 90th percentile AQI 741999: 90th percentile AQI 742000: 90th percentile AQI 742001: 90th percentile AQI 742002: 90th percentile AQI 772003: 90th percentile AQI 712004: 90th percentile AQI 612005: 90th percentile AQI 842006: 90th percentile AQI 902007: 90th percentile AQI 742008: 90th percentile AQI 802009: 90th percentile AQI 612010: 90th percentile AQI 672011: 90th percentile AQI 772012: 90th percentile AQI 802013: 90th percentile AQI 582014: 90th percentile AQI 612015: 90th percentile AQI 612016: 90th percentile AQI 612017: 90th percentile AQI 742018: 90th percentile AQI 712019: 90th percentile AQI 712020: 90th percentile AQI 632021: 90th percentile AQI 772022: 90th percentile AQI 542023: 90th percentile AQI 772024: 90th percentile AQI 742025: 90th percentile AQI 641988: Median AQI 151989: Median AQI 131990: Median AQI 441991: Median AQI 451992: Median AQI 441993: Median AQI 441994: Median AQI 461995: Median AQI 441996: Median AQI 441997: Median AQI 471998: Median AQI 491999: Median AQI 482000: Median AQI 472001: Median AQI 482002: Median AQI 442003: Median AQI 432004: Median AQI 452005: Median AQI 512006: Median AQI 542007: Median AQI 502008: Median AQI 492009: Median AQI 452010: Median AQI 482011: Median AQI 502012: Median AQI 502013: Median AQI 462014: Median AQI 462015: Median AQI 452016: Median AQI 452017: Median AQI 482018: Median AQI 472019: Median AQI 462020: Median AQI 452021: Median AQI 462022: Median AQI 452023: Median AQI 472024: Median AQI 462025: Median AQI 47198819931998200320082013201820232025
  • 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
Ozone35096%
Fine particles (PM2.5)154%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536525610423004764164Ozone
202436624411570004674115Ozone
202336523712260004777122Ozone
20223653016310004554105Ozone
202136525310570004677133Ozone
20203662897241004563151Ozone
20193652658983004671200Ozone
20183652301350000477197Ozone
201736522013780004874150Ozone
20163662877810004561102Ozone
20153652887610004561101Ozone
20143652729300004661100Ozone
20133652739200004658100Ozone
201236619016195105080219Ozone
2011365194154122305077219Ozone
201036523313020004867112Ozone
20093652689700004561100Ozone
200836620414696104980218Ozone
200736519516730005074106Ozone
2006365149204111005490166Ozone
2005365175175123005184179Ozone
2004364284800000456190Ozone
20033072267830004371105Ozone
20023612619550004477119Ozone
200135823312320004874101Ozone
200036222912580004774129Ozone
199936120415070004874126Ozone
199836222513340004974101Ozone
199736425310920004767112Ozone
19962501717720004474147Ozone
1995252209430000445887Ozone
199435925110800004664100Ozone
1993343283600000445484Ozone
1992354275790000446493Ozone
19913342656900004561100Ozone
19903633006300004454100Ozone
1989969600000132742PM2.5
1988707000000153243PM2.5

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 Wyoming with a similar median AQI in 2025

All monitored counties in Wyoming

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