EnviroNearby

Washington County, Kentucky air quality history

Daily Air Quality Index summaries from EPA monitors in Washington, Kentucky, 1990–2025.

90%
Good days in 2025
38
Median daily AQI, 2025
0
Days above 100 in 2025
360
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Washington, Kentucky on 360 days. 325 of those days (90%) were in the Good range, and the median daily AQI was 38. That median is about the same as the typical monitored county in Kentucky (median 39 across 25 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 360 days. Across the years with fuller monitoring, the share of Good days rose: an average of 69% in 1990–1992 versus 90% 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%1990: Good 93 of 148 days1990: Moderate 31 of 148 days1990: Unhealthy for Sensitive Groups 21 of 148 days1990: Unhealthy 3 of 148 days19901991: Good 235 of 343 days1991: Moderate 82 of 343 days1991: Unhealthy for Sensitive Groups 24 of 343 days1991: Unhealthy 2 of 343 days1992: Good 267 of 360 days1992: Moderate 79 of 360 days1992: Unhealthy for Sensitive Groups 13 of 360 days1992: Unhealthy 1 of 360 days1993: Good 228 of 356 days1993: Moderate 102 of 356 days1993: Unhealthy for Sensitive Groups 23 of 356 days1993: Unhealthy 3 of 356 days1994: Good 230 of 352 days1994: Moderate 88 of 352 days1994: Unhealthy for Sensitive Groups 23 of 352 days1994: Unhealthy 11 of 352 days1995: Good 140 of 263 days1995: Moderate 87 of 263 days1995: Unhealthy for Sensitive Groups 26 of 263 days1995: Unhealthy 10 of 263 days19951996: Good 127 of 212 days1996: Moderate 62 of 212 days1996: Unhealthy for Sensitive Groups 21 of 212 days1996: Unhealthy 2 of 212 days1997: Good 249 of 360 days1997: Moderate 82 of 360 days1997: Unhealthy for Sensitive Groups 26 of 360 days1997: Unhealthy 3 of 360 days1998: Good 218 of 357 days1998: Moderate 76 of 357 days1998: Unhealthy for Sensitive Groups 49 of 357 days1998: Unhealthy 12 of 357 days1998: Very Unhealthy 2 of 357 days1999: Good 205 of 363 days1999: Moderate 93 of 363 days1999: Unhealthy for Sensitive Groups 53 of 363 days1999: Unhealthy 11 of 363 days1999: Very Unhealthy 1 of 363 days2000: Good 223 of 358 days2000: Moderate 106 of 358 days2000: Unhealthy for Sensitive Groups 28 of 358 days2000: Unhealthy 1 of 358 days20002001: Good 243 of 361 days2001: Moderate 98 of 361 days2001: Unhealthy for Sensitive Groups 20 of 361 days2002: Good 257 of 362 days2002: Moderate 69 of 362 days2002: Unhealthy for Sensitive Groups 27 of 362 days2002: Unhealthy 9 of 362 days2003: Good 270 of 355 days2003: Moderate 77 of 355 days2003: Unhealthy for Sensitive Groups 8 of 355 days2004: Good 302 of 361 days2004: Moderate 58 of 361 days2004: Unhealthy for Sensitive Groups 1 of 361 days2005: Good 257 of 363 days2005: Moderate 86 of 363 days2005: Unhealthy for Sensitive Groups 19 of 363 days2005: Unhealthy 1 of 363 days20052006: Good 278 of 364 days2006: Moderate 79 of 364 days2006: Unhealthy for Sensitive Groups 7 of 364 days2007: Good 227 of 364 days2007: Moderate 109 of 364 days2007: Unhealthy for Sensitive Groups 27 of 364 days2007: Unhealthy 1 of 364 days2008: Good 259 of 358 days2008: Moderate 98 of 358 days2008: Unhealthy for Sensitive Groups 1 of 358 days2009: Good 294 of 337 days2009: Moderate 43 of 337 days2010: Good 271 of 361 days2010: Moderate 85 of 361 days2010: Unhealthy for Sensitive Groups 5 of 361 days20102011: Good 272 of 339 days2011: Moderate 64 of 339 days2011: Unhealthy for Sensitive Groups 3 of 339 days2012: Good 280 of 364 days2012: Moderate 72 of 364 days2012: Unhealthy for Sensitive Groups 12 of 364 days2013: Good 334 of 362 days2013: Moderate 28 of 362 days2014: Good 314 of 362 days2014: Moderate 47 of 362 days2014: Unhealthy for Sensitive Groups 1 of 362 days2015: Good 333 of 360 days2015: Moderate 26 of 360 days2015: Unhealthy for Sensitive Groups 1 of 360 days20152016: Good 326 of 359 days2016: Moderate 33 of 359 days2017: Good 332 of 362 days2017: Moderate 29 of 362 days2017: Unhealthy for Sensitive Groups 1 of 362 days2018: Good 326 of 359 days2018: Moderate 33 of 359 days2019: Good 331 of 364 days2019: Moderate 33 of 364 days2020: Good 352 of 364 days2020: Moderate 12 of 364 days20202021: Good 342 of 362 days2021: Moderate 20 of 362 days2022: Good 340 of 364 days2022: Moderate 24 of 364 days2023: Good 315 of 358 days2023: Moderate 41 of 358 days2023: Unhealthy for Sensitive Groups 2 of 358 days2024: Good 315 of 349 days2024: Moderate 34 of 349 days2025: Good 325 of 360 days2025: Moderate 35 of 360 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 year0501001501990: 90th percentile AQI 1121991: 90th percentile AQI 901992: 90th percentile AQI 841993: 90th percentile AQI 931994: 90th percentile AQI 1001995: 90th percentile AQI 1151996: 90th percentile AQI 1011997: 90th percentile AQI 971998: 90th percentile AQI 1221999: 90th percentile AQI 1292000: 90th percentile AQI 972001: 90th percentile AQI 902002: 90th percentile AQI 1002003: 90th percentile AQI 712004: 90th percentile AQI 612005: 90th percentile AQI 842006: 90th percentile AQI 772007: 90th percentile AQI 932008: 90th percentile AQI 712009: 90th percentile AQI 542010: 90th percentile AQI 672011: 90th percentile AQI 642012: 90th percentile AQI 772013: 90th percentile AQI 492014: 90th percentile AQI 542015: 90th percentile AQI 492016: 90th percentile AQI 502017: 90th percentile AQI 492018: 90th percentile AQI 502019: 90th percentile AQI 502020: 90th percentile AQI 462021: 90th percentile AQI 472022: 90th percentile AQI 492023: 90th percentile AQI 512024: 90th percentile AQI 502025: 90th percentile AQI 501990: Median AQI 421991: Median AQI 411992: Median AQI 421993: Median AQI 421994: Median AQI 441995: Median AQI 491996: Median AQI 451997: Median AQI 421998: Median AQI 441999: Median AQI 462000: Median AQI 442001: Median AQI 442002: Median AQI 412003: Median AQI 402004: Median AQI 372005: Median AQI 392006: Median AQI 412007: Median AQI 442008: Median AQI 412009: Median AQI 372010: Median AQI 412011: Median AQI 402012: Median AQI 422013: Median AQI 382014: Median AQI 372015: Median AQI 372016: Median AQI 382017: Median AQI 382018: Median AQI 352019: Median AQI 392020: Median AQI 342021: Median AQI 362022: Median AQI 372023: Median AQI 402024: Median AQI 392025: Median AQI 3819901995200020052010201520202025
  • 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
Ozone360100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025360325350000385097Ozone
2024349315340000395074Ozone
20233583154120004051108Ozone
2022364340240000374977Ozone
2021362342200000364787Ozone
2020364352120000344677Ozone
2019364331330000395080Ozone
2018359326330000355077Ozone
20173623322910003849112Ozone
2016359326330000385090Ozone
20153603332610003749101Ozone
20143623144710003754101Ozone
2013362334280000384993Ozone
201236428072120004277150Ozone
20113392726430004064112Ozone
20103612718550004167126Ozone
2009337294430000375487Ozone
20083582599810004171112Ozone
2007364227109271004493151Ozone
20063642787970004177122Ozone
200536325786191003984161Ozone
20043613025810003761101Ozone
20033552707780004071140Ozone
2002362257692790041100197Ozone
200136124398200004490140Ozone
2000358223106281004497151Ozone
19993632059353111046129204Ozone
19983572187649122044122208Ozone
199736024982263004297174Ozone
1996212127622120045101174Ozone
19952631408726100049115179Ozone
19943522308823110044100192Ozone
1993356228102233004293179Ozone
199236026779131004284164Ozone
199134323582242004190172Ozone
199014893312130042112185Ozone

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 Kentucky with a similar median AQI in 2025

All monitored counties in Kentucky

Source: U.S. EPA AirData, “Annual AQI by County” files for 1990–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem