EnviroNearby

Teton County, Wyoming air quality history

Daily Air Quality Index summaries from EPA monitors in Teton, Wyoming, 1985–2025.

85%
Good days in 2025
44
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 Teton, Wyoming on 365 days. 310 of those days (85%) were in the Good range, and the median daily AQI was 44. 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 351 days. Across the years with fuller monitoring, the share of Good days fell: an average of 89% in 1987–1989 versus 83% in 2023–2025.

Years with fewer than 120 monitored days (1985, 1986) 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 3 of 3 days19851986: Good 37 of 41 days1986: Moderate 4 of 41 days1987: Good 196 of 205 days1987: Moderate 8 of 205 days1987: Unhealthy for Sensitive Groups 1 of 205 days1988: Good 256 of 309 days1988: Moderate 50 of 309 days1988: Unhealthy for Sensitive Groups 3 of 309 days1989: Good 244 of 274 days1989: Moderate 30 of 274 days1990: Good 329 of 340 days1990: Moderate 11 of 340 days19901991: Good 304 of 321 days1991: Moderate 17 of 321 days1992: Good 307 of 335 days1992: Moderate 28 of 335 days1993: Good 326 of 334 days1993: Moderate 8 of 334 days1994: Good 296 of 347 days1994: Moderate 51 of 347 days1995: Good 303 of 337 days1995: Moderate 34 of 337 days19951996: Good 293 of 345 days1996: Moderate 52 of 345 days1997: Good 321 of 350 days1997: Moderate 29 of 350 days1998: Good 312 of 360 days1998: Moderate 48 of 360 days1999: Good 256 of 355 days1999: Moderate 95 of 355 days1999: Unhealthy for Sensitive Groups 4 of 355 days2000: Good 288 of 361 days2000: Moderate 73 of 361 days20002001: Good 281 of 362 days2001: Moderate 81 of 362 days2002: Good 266 of 364 days2002: Moderate 98 of 364 days2003: Good 252 of 331 days2003: Moderate 78 of 331 days2003: Unhealthy for Sensitive Groups 1 of 331 days2004: Good 300 of 354 days2004: Moderate 54 of 354 days2005: Good 307 of 364 days2005: Moderate 56 of 364 days2005: Unhealthy for Sensitive Groups 1 of 364 days20052006: Good 252 of 364 days2006: Moderate 111 of 364 days2006: Unhealthy for Sensitive Groups 1 of 364 days2007: Good 297 of 365 days2007: Moderate 68 of 365 days2008: Good 307 of 366 days2008: Moderate 59 of 366 days2009: Good 326 of 365 days2009: Moderate 37 of 365 days2009: Unhealthy for Sensitive Groups 1 of 365 days2009: Unhealthy 1 of 365 days2010: Good 279 of 365 days2010: Moderate 86 of 365 days20102011: Good 269 of 365 days2011: Moderate 96 of 365 days2012: Good 252 of 366 days2012: Moderate 111 of 366 days2012: Unhealthy for Sensitive Groups 3 of 366 days2013: Good 303 of 365 days2013: Moderate 62 of 365 days2014: Good 317 of 365 days2014: Moderate 48 of 365 days2015: Good 322 of 365 days2015: Moderate 42 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days20152016: Good 324 of 366 days2016: Moderate 42 of 366 days2017: Good 289 of 365 days2017: Moderate 75 of 365 days2017: Unhealthy for Sensitive Groups 1 of 365 days2018: Good 273 of 365 days2018: Moderate 91 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days2019: Good 323 of 365 days2019: Moderate 42 of 365 days2020: Good 312 of 366 days2020: Moderate 42 of 366 days2020: Unhealthy for Sensitive Groups 7 of 366 days2020: Unhealthy 5 of 366 days20202021: Good 277 of 365 days2021: Moderate 78 of 365 days2021: Unhealthy for Sensitive Groups 10 of 365 days2022: Good 332 of 365 days2022: Moderate 33 of 365 days2023: Good 321 of 365 days2023: Moderate 44 of 365 days2024: Good 276 of 366 days2024: Moderate 88 of 366 days2024: Unhealthy for Sensitive Groups 2 of 366 days2025: Good 310 of 365 days2025: Moderate 55 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 341986: 90th percentile AQI 491987: 90th percentile AQI 471988: 90th percentile AQI 561989: 90th percentile AQI 511990: 90th percentile AQI 431991: 90th percentile AQI 461992: 90th percentile AQI 491993: 90th percentile AQI 461994: 90th percentile AQI 541995: 90th percentile AQI 511996: 90th percentile AQI 541997: 90th percentile AQI 491998: 90th percentile AQI 541999: 90th percentile AQI 712000: 90th percentile AQI 622001: 90th percentile AQI 642002: 90th percentile AQI 672003: 90th percentile AQI 642004: 90th percentile AQI 542005: 90th percentile AQI 542006: 90th percentile AQI 712007: 90th percentile AQI 582008: 90th percentile AQI 582009: 90th percentile AQI 512010: 90th percentile AQI 612011: 90th percentile AQI 642012: 90th percentile AQI 672013: 90th percentile AQI 582014: 90th percentile AQI 512015: 90th percentile AQI 532016: 90th percentile AQI 522017: 90th percentile AQI 612018: 90th percentile AQI 642019: 90th percentile AQI 512020: 90th percentile AQI 572021: 90th percentile AQI 722022: 90th percentile AQI 502023: 90th percentile AQI 512024: 90th percentile AQI 672025: 90th percentile AQI 541985: Median AQI 261986: Median AQI 311987: Median AQI 381988: Median AQI 401989: Median AQI 381990: Median AQI 341991: Median AQI 391992: Median AQI 381993: Median AQI 381994: Median AQI 441995: Median AQI 411996: Median AQI 391997: Median AQI 401998: Median AQI 421999: Median AQI 452000: Median AQI 442001: Median AQI 452002: Median AQI 452003: Median AQI 442004: Median AQI 432005: Median AQI 442006: Median AQI 452007: Median AQI 442008: Median AQI 422009: Median AQI 422010: Median AQI 442011: Median AQI 452012: Median AQI 452013: Median AQI 442014: Median AQI 422015: Median AQI 422016: Median AQI 422017: Median AQI 442018: Median AQI 442019: Median AQI 442020: Median AQI 432021: Median AQI 442022: Median AQI 432023: Median AQI 432024: Median AQI 442025: Median AQI 44198519901995200020052010201520202025
  • 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
Ozone35196%
Fine particles (PM2.5)134%
Coarse particles (PM10)1<1%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365310550000445490Ozone
20243662768820004467138Ozone
2023365321440000435175Ozone
20223653323300004350100Ozone
202136527778100004472131Ozone
20203663124275004357165Ozone
2019365323420000445187Ozone
20183652739110004464106Ozone
20173652897510004461118Ozone
2016366324420000425299Ozone
20153653224210004253107Ozone
2014365317480000425197Ozone
2013365303620000445880Ozone
201236625211130004567110Ozone
2011365269960000456490Ozone
2010365279860000446190Ozone
20093653263711004251169Ozone
2008366307590000425893Ozone
2007365297680000445897Ozone
200636425211110004571140Ozone
20053643075610004454106Ozone
2004354300540000435494Ozone
20033312527810004464101Ozone
20023642669800004567100Ozone
2001362281810000456493Ozone
20003612887300004462100Ozone
19993552569540004571126Ozone
1998360312480000425497Ozone
1997350321290000404984Ozone
19963452935200003954100Ozone
1995337303340000415180Ozone
1994347296510000445490Ozone
199333432680000384682Ozone
1992335307280000384990Ozone
1991321304170000394667Ozone
1990340329110000344376Ozone
1989274244300000385190Ozone
19883092565030004056147Ozone
1987205196810003847101Ozone
1986413740000314959PM10
19853300000263434PM10

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 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