EnviroNearby

Converse County, Wyoming air quality history

Daily Air Quality Index summaries from EPA monitors in Converse, Wyoming, 1995–2025.

96%
Good days in 2025
40
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 Converse, Wyoming on 365 days. 351 of those days (96%) were in the Good range, and the median daily AQI was 40. That median is about the same as the typical monitored county in Wyoming (median 41 across 17 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 323 days. Across the years with fuller monitoring, the share of Good days fell: an average of 95% in 2002–2004 versus 90% in 2023–2025.

Years with fewer than 120 monitored days (1996, 1997, 1998, 1999, 2000, 2001…) 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%1995: Good 51 of 51 days19951996: Good 43 of 43 days1997: Good 61 of 62 days1997: Moderate 1 of 62 days1998: Good 59 of 61 days1998: Moderate 2 of 61 days1999: Good 56 of 60 days1999: Moderate 4 of 60 days2000: Good 89 of 96 days2000: Moderate 7 of 96 days20002001: Good 59 of 65 days2001: Moderate 6 of 65 days2002: Good 117 of 125 days2002: Moderate 8 of 125 days2003: Good 323 of 335 days2003: Moderate 12 of 335 days2004: Good 339 of 354 days2004: Moderate 15 of 354 days2005: Good 280 of 298 days2005: Moderate 17 of 298 days2005: Unhealthy for Sensitive Groups 1 of 298 days20052006: Good 266 of 287 days2006: Moderate 21 of 287 days2007: Good 85 of 120 days2007: Moderate 35 of 120 days2008: Good 98 of 121 days2008: Moderate 23 of 121 days2009: Good 315 of 340 days2009: Moderate 25 of 340 days2010: Good 337 of 363 days2010: Moderate 26 of 363 days20102011: Good 335 of 360 days2011: Moderate 25 of 360 days2012: Good 296 of 360 days2012: Moderate 62 of 360 days2012: Unhealthy for Sensitive Groups 2 of 360 days2013: Good 295 of 365 days2013: Moderate 68 of 365 days2013: Unhealthy for Sensitive Groups 2 of 365 days2014: Good 308 of 365 days2014: Moderate 57 of 365 days2015: Good 288 of 365 days2015: Moderate 72 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days2015: Unhealthy 2 of 365 days20152016: Good 311 of 366 days2016: Moderate 54 of 366 days2016: Unhealthy 1 of 366 days2017: Good 282 of 365 days2017: Moderate 80 of 365 days2017: Unhealthy for Sensitive Groups 3 of 365 days2018: Good 310 of 365 days2018: Moderate 54 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days2019: Good 314 of 365 days2019: Moderate 50 of 365 days2019: Unhealthy for Sensitive Groups 1 of 365 days2020: Good 302 of 366 days2020: Moderate 60 of 366 days2020: Unhealthy for Sensitive Groups 4 of 366 days20202021: Good 274 of 365 days2021: Moderate 87 of 365 days2021: Unhealthy for Sensitive Groups 4 of 365 days2022: Good 314 of 365 days2022: Moderate 51 of 365 days2023: Good 331 of 365 days2023: Moderate 34 of 365 days2024: Good 305 of 366 days2024: Moderate 57 of 366 days2024: Unhealthy for Sensitive Groups 4 of 366 days2025: Good 351 of 365 days2025: Moderate 14 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 year0501001995: 90th percentile AQI 201996: 90th percentile AQI 221997: 90th percentile AQI 351998: 90th percentile AQI 391999: 90th percentile AQI 462000: 90th percentile AQI 442001: 90th percentile AQI 482002: 90th percentile AQI 442003: 90th percentile AQI 382004: 90th percentile AQI 432005: 90th percentile AQI 422006: 90th percentile AQI 452007: 90th percentile AQI 602008: 90th percentile AQI 562009: 90th percentile AQI 442010: 90th percentile AQI 472011: 90th percentile AQI 442012: 90th percentile AQI 572013: 90th percentile AQI 612014: 90th percentile AQI 542015: 90th percentile AQI 612016: 90th percentile AQI 532017: 90th percentile AQI 612018: 90th percentile AQI 552019: 90th percentile AQI 532020: 90th percentile AQI 612021: 90th percentile AQI 702022: 90th percentile AQI 542023: 90th percentile AQI 492024: 90th percentile AQI 582025: 90th percentile AQI 491995: Median AQI 91996: Median AQI 91997: Median AQI 161998: Median AQI 211999: Median AQI 232000: Median AQI 232001: Median AQI 262002: Median AQI 282003: Median AQI 172004: Median AQI 142005: Median AQI 182006: Median AQI 182007: Median AQI 362008: Median AQI 332009: Median AQI 232010: Median AQI 232011: Median AQI 222012: Median AQI 292013: Median AQI 422014: Median AQI 422015: Median AQI 432016: Median AQI 412017: Median AQI 422018: Median AQI 412019: Median AQI 412020: Median AQI 422021: Median AQI 422022: Median AQI 402023: Median AQI 422024: Median AQI 412025: Median AQI 401995200020052010201520202025
  • 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
Ozone32388%
Coarse particles (PM10)4111%
Nitrogen dioxide (NO₂)1<1%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365351140000404963Ozone
20243663055740004158126Ozone
2023365331340000424999Ozone
2022365314510000405490Ozone
20213652748740004270119Ozone
20203663026040004261129Ozone
20193653145010004153101Ozone
20183653105410004155102Ozone
20173652828030004261121Ozone
20163663115401004153173Ozone
20153652887232004361161Ozone
2014365308570000425487Ozone
20133652956820004261108Ozone
20123602966220002957129PM10
2011360335250000224489PM10
2010363337260000234799PM10
20093403152500002344100PM10
200812198230000335681PM10
200712085350000366078PM10
2006287266210000184596NO2
20052982801710001842125NO2
2004354339150000144370NO2
2003335323120000173888NO2
200212511780000284485PM10
2001655960000264891PM10
2000968970000234462PM2.5
1999605640000234664PM10
1998615920000213972PM10
1997626110000163552PM10
199643430000092242PM10
199551510000092035PM10

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 1995–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem