EnviroNearby

Trego County, Kansas air quality history

Daily Air Quality Index summaries from EPA monitors in Trego, Kansas, 2000–2025.

76%
Good days in 2025
41
Median daily AQI, 2025
1
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Trego, Kansas on 364 days. 275 of those days (76%) were in the Good range, and the median daily AQI was 41. That median is lower than the typical monitored county in Kansas (median 44 across 11 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 254 days. Across the years with fuller monitoring, the share of Good days fell: an average of 77% in 2000–2002 versus 68% 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%2000: Good 145 of 257 days2000: Moderate 94 of 257 days2000: Unhealthy for Sensitive Groups 17 of 257 days2000: Unhealthy 1 of 257 days20002001: Good 280 of 365 days2001: Moderate 71 of 365 days2001: Unhealthy for Sensitive Groups 14 of 365 days2002: Good 354 of 364 days2002: Moderate 9 of 364 days2002: Unhealthy for Sensitive Groups 1 of 364 days20022003: Good 323 of 365 days2003: Moderate 41 of 365 days2003: Unhealthy for Sensitive Groups 1 of 365 days2004: Good 261 of 361 days2004: Moderate 96 of 361 days2004: Unhealthy for Sensitive Groups 4 of 361 days20042005: Good 258 of 344 days2005: Moderate 80 of 344 days2005: Unhealthy for Sensitive Groups 6 of 344 days2006: Good 239 of 363 days2006: Moderate 105 of 363 days2006: Unhealthy for Sensitive Groups 19 of 363 days20062007: Good 272 of 337 days2007: Moderate 64 of 337 days2007: Unhealthy for Sensitive Groups 1 of 337 days2008: Good 296 of 363 days2008: Moderate 67 of 363 days20082009: Good 298 of 365 days2009: Moderate 66 of 365 days2009: Unhealthy for Sensitive Groups 1 of 365 days2010: Good 270 of 364 days2010: Moderate 90 of 364 days2010: Unhealthy for Sensitive Groups 4 of 364 days20102011: Good 252 of 365 days2011: Moderate 102 of 365 days2011: Unhealthy for Sensitive Groups 11 of 365 days2012: Good 255 of 366 days2012: Moderate 98 of 366 days2012: Unhealthy for Sensitive Groups 13 of 366 days20122013: Good 295 of 363 days2013: Moderate 68 of 363 days2014: Good 283 of 362 days2014: Moderate 79 of 362 days20142015: Good 297 of 358 days2015: Moderate 60 of 358 days2015: Unhealthy for Sensitive Groups 1 of 358 days2016: Good 334 of 366 days2016: Moderate 32 of 366 days20162017: Good 334 of 365 days2017: Moderate 31 of 365 days2018: Good 287 of 364 days2018: Moderate 76 of 364 days2018: Unhealthy for Sensitive Groups 1 of 364 days20182019: Good 310 of 364 days2019: Moderate 54 of 364 days2020: Good 307 of 365 days2020: Moderate 57 of 365 days2020: Unhealthy for Sensitive Groups 1 of 365 days20202021: Good 248 of 362 days2021: Moderate 108 of 362 days2021: Unhealthy for Sensitive Groups 5 of 362 days2021: Hazardous 1 of 362 days2022: Good 266 of 360 days2022: Moderate 91 of 360 days2022: Unhealthy for Sensitive Groups 2 of 360 days2022: Unhealthy 1 of 360 days20222023: Good 211 of 365 days2023: Moderate 149 of 365 days2023: Unhealthy for Sensitive Groups 4 of 365 days2023: Unhealthy 1 of 365 days2024: Good 261 of 365 days2024: Moderate 100 of 365 days2024: Unhealthy for Sensitive Groups 4 of 365 days20242025: Good 275 of 364 days2025: Moderate 88 of 364 days2025: Unhealthy for Sensitive Groups 1 of 364 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 year0501002000: 90th percentile AQI 932001: 90th percentile AQI 772002: 90th percentile AQI 382003: 90th percentile AQI 532004: 90th percentile AQI 712005: 90th percentile AQI 712006: 90th percentile AQI 902007: 90th percentile AQI 582008: 90th percentile AQI 582009: 90th percentile AQI 612010: 90th percentile AQI 642011: 90th percentile AQI 772012: 90th percentile AQI 772013: 90th percentile AQI 582014: 90th percentile AQI 642015: 90th percentile AQI 582016: 90th percentile AQI 502017: 90th percentile AQI 492018: 90th percentile AQI 612019: 90th percentile AQI 532020: 90th percentile AQI 542021: 90th percentile AQI 662022: 90th percentile AQI 612023: 90th percentile AQI 712024: 90th percentile AQI 672025: 90th percentile AQI 612000: Median AQI 482001: Median AQI 352002: Median AQI 242003: Median AQI 272004: Median AQI 432005: Median AQI 422006: Median AQI 442007: Median AQI 422008: Median AQI 402009: Median AQI 392010: Median AQI 432011: Median AQI 432012: Median AQI 422013: Median AQI 402014: Median AQI 412015: Median AQI 412016: Median AQI 392017: Median AQI 362018: Median AQI 392019: Median AQI 372020: Median AQI 382021: Median AQI 432022: Median AQI 422023: Median AQI 472024: Median AQI 442025: Median AQI 4120002002200420062008201020122014201620182020202220242025
  • 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
Ozone25470%
Fine particles (PM2.5)10027%
Coarse particles (PM10)103%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253642758810004161116Ozone
202436526110040004467127Ozone
202336521114941004771164Ozone
20223602669121004261154Ozone
202136224810850014366318Ozone
20203653075710003854147Ozone
2019364310540000375399Ozone
20183642877610003961130Ozone
2017365334310000364984Ozone
2016366334320000395067Ozone
20153582976010004158128Ozone
2014362283790000416497Ozone
2013363295680000405893Ozone
201236625598130004277143Ozone
2011365252102110004377133Ozone
20103642709040004364108Ozone
20093652986610003961112Ozone
2008363296670000405884Ozone
20073372726410004258108Ozone
2006363239105190004490122Ozone
20053442588060004271112Ozone
20043612619640004371115Ozone
20033653234110002753101Ozone
2002364354910002438101Ozone
200136528071140003577129Ozone
200025714594171004893161Ozone

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 Kansas with a similar median AQI in 2025

All monitored counties in Kansas

Source: U.S. EPA AirData, “Annual AQI by County” files for 2000–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem