EnviroNearby

Lincoln County, Wyoming air quality history

Daily Air Quality Index summaries from EPA monitors in Lincoln, Wyoming, 1994–2025.

99%
Good days in 2025
10
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 Lincoln, Wyoming on 365 days. 361 of those days (99%) were in the Good range, and the median daily AQI was 10. That median is lower than the typical monitored county in Wyoming (median 41 across 17 counties), and lower than the typical monitored U.S. county (40). The main pollutant was coarse particles (PM10) on 365 days. Across the years with fuller monitoring, the share of Good days rose: an average of 83% in 1994–1996 versus 91% in 2023–2025.

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%1994: Good 239 of 360 days1994: Moderate 93 of 360 days1994: Unhealthy for Sensitive Groups 17 of 360 days1994: Unhealthy 5 of 360 days1994: Very Unhealthy 1 of 360 days1994: Hazardous 5 of 360 days19941995: Good 179 of 212 days1995: Moderate 26 of 212 days1995: Unhealthy for Sensitive Groups 4 of 212 days1995: Unhealthy 1 of 212 days1995: Very Unhealthy 1 of 212 days1995: Hazardous 1 of 212 days1996: Good 207 of 213 days1996: Moderate 6 of 213 days1997: Good 208 of 211 days1997: Moderate 3 of 211 days1998: Good 287 of 289 days1998: Moderate 2 of 289 days1999: Good 343 of 359 days1999: Moderate 14 of 359 days1999: Unhealthy for Sensitive Groups 2 of 359 days19992000: Good 346 of 359 days2000: Moderate 12 of 359 days2000: Unhealthy for Sensitive Groups 1 of 359 days2001: Good 326 of 329 days2001: Moderate 3 of 329 days2002: Good 341 of 358 days2002: Moderate 17 of 358 days2003: Good 349 of 365 days2003: Moderate 15 of 365 days2003: Unhealthy for Sensitive Groups 1 of 365 days2004: Good 341 of 366 days2004: Moderate 25 of 366 days20042005: Good 359 of 363 days2005: Moderate 4 of 363 days2006: Good 354 of 360 days2006: Moderate 5 of 360 days2006: Very Unhealthy 1 of 360 days2007: Good 332 of 343 days2007: Moderate 11 of 343 days2008: Good 339 of 366 days2008: Moderate 26 of 366 days2008: Unhealthy for Sensitive Groups 1 of 366 days2009: Good 315 of 365 days2009: Moderate 48 of 365 days2009: Unhealthy for Sensitive Groups 2 of 365 days20092010: Good 341 of 362 days2010: Moderate 21 of 362 days2011: Good 341 of 365 days2011: Moderate 24 of 365 days2012: Good 315 of 366 days2012: Moderate 45 of 366 days2012: Unhealthy for Sensitive Groups 4 of 366 days2012: Unhealthy 2 of 366 days2013: Good 338 of 365 days2013: Moderate 26 of 365 days2013: Unhealthy 1 of 365 days2014: Good 358 of 365 days2014: Moderate 7 of 365 days20142015: Good 355 of 365 days2015: Moderate 10 of 365 days2016: Good 363 of 366 days2016: Moderate 3 of 366 days2017: Good 348 of 365 days2017: Moderate 16 of 365 days2017: Very Unhealthy 1 of 365 days2018: Good 343 of 365 days2018: Moderate 22 of 365 days2019: Good 364 of 365 days2019: Moderate 1 of 365 days20192020: Good 357 of 366 days2020: Moderate 9 of 366 days2021: Good 297 of 365 days2021: Moderate 62 of 365 days2021: Unhealthy for Sensitive Groups 6 of 365 days2022: Good 321 of 365 days2022: Moderate 43 of 365 days2022: Unhealthy for Sensitive Groups 1 of 365 days2023: Good 298 of 365 days2023: Moderate 67 of 365 days2024: Good 340 of 366 days2024: Moderate 26 of 366 days20242025: Good 361 of 365 days2025: Moderate 4 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 year0501001994: 90th percentile AQI 881995: 90th percentile AQI 551996: 90th percentile AQI 371997: 90th percentile AQI 291998: 90th percentile AQI 231999: 90th percentile AQI 392000: 90th percentile AQI 342001: 90th percentile AQI 312002: 90th percentile AQI 392003: 90th percentile AQI 362004: 90th percentile AQI 402005: 90th percentile AQI 212006: 90th percentile AQI 312007: 90th percentile AQI 372008: 90th percentile AQI 452009: 90th percentile AQI 532010: 90th percentile AQI 412011: 90th percentile AQI 372012: 90th percentile AQI 542013: 90th percentile AQI 472014: 90th percentile AQI 312015: 90th percentile AQI 342016: 90th percentile AQI 332017: 90th percentile AQI 342018: 90th percentile AQI 442019: 90th percentile AQI 272020: 90th percentile AQI 342021: 90th percentile AQI 672022: 90th percentile AQI 512023: 90th percentile AQI 582024: 90th percentile AQI 482025: 90th percentile AQI 261994: Median AQI 341995: Median AQI 191996: Median AQI 171997: Median AQI 161998: Median AQI 121999: Median AQI 172000: Median AQI 152001: Median AQI 152002: Median AQI 162003: Median AQI 152004: Median AQI 132005: Median AQI 102006: Median AQI 152007: Median AQI 182008: Median AQI 182009: Median AQI 192010: Median AQI 172011: Median AQI 152012: Median AQI 192013: Median AQI 192014: Median AQI 142015: Median AQI 132016: Median AQI 132017: Median AQI 142018: Median AQI 162019: Median AQI 122020: Median AQI 152021: Median AQI 302022: Median AQI 432023: Median AQI 442024: Median AQI 312025: Median AQI 1019941999200420092014201920242025
  • 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
Coarse particles (PM10)365100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536536140000102677PM10
2024366340260000314877PM10
2023365298670000445897Ozone
20223653214310004351118Ozone
20213652976260003067126PM10
202036635790000153471PM10
201936536410000122756PM10
2018365343220000164482PM10
20173653481600101434208PM10
201636636330000133369PM10
2015365355100000133496PM10
201436535870000143169PM10
20133653382601001947160PM10
20123663154542001954186PM10
2011365341240000153789PM10
2010362341210000174188PM10
20093653154820001953116PM10
20083663392610001845124PM10
2007343332110000183790PM10
2006360354500101531299PM10
200536335940000102157PM10
2004366341250000134078PM10
20033653491510001536118PM10
2002358341170000163978PM10
200132932630000153159PM10
20003593461210001534108PM10
19993593431420001739140PM10
199828928720000122354PM10
199721120830000162984PM10
199621320760000173770PM10
19952121792641111955617PM10
199436023993175153488808PM10

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 1994–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem