EnviroNearby

Franklin County, Washington air quality history

Daily Air Quality Index summaries from EPA monitors in Franklin, Washington, 2003–2025.

87%
Good days in 2025
23
Median daily AQI, 2025
2
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 Franklin, Washington on 360 days. 312 of those days (87%) were in the Good range, and the median daily AQI was 23. That median is lower than the typical monitored county in Washington (median 28 across 30 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 360 days. Across the years with fuller monitoring, the share of Good days rose: an average of 84% in 2003–2005 versus 88% 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%2003: Good 293 of 349 days2003: Moderate 56 of 349 days20032004: Good 296 of 366 days2004: Moderate 70 of 366 days2005: Good 318 of 365 days2005: Moderate 47 of 365 days20052006: Good 302 of 351 days2006: Moderate 49 of 351 days2007: Good 296 of 363 days2007: Moderate 67 of 363 days20072008: Good 308 of 366 days2008: Moderate 58 of 366 days2009: Good 323 of 365 days2009: Moderate 42 of 365 days20092010: Good 330 of 365 days2010: Moderate 35 of 365 days2011: Good 321 of 363 days2011: Moderate 42 of 363 days20112012: Good 310 of 359 days2012: Moderate 48 of 359 days2012: Unhealthy for Sensitive Groups 1 of 359 days2013: Good 259 of 333 days2013: Moderate 74 of 333 days20132014: Good 272 of 311 days2014: Moderate 39 of 311 days2015: Good 300 of 359 days2015: Moderate 56 of 359 days2015: Unhealthy for Sensitive Groups 3 of 359 days20152016: Good 318 of 332 days2016: Moderate 14 of 332 days2017: Good 261 of 331 days2017: Moderate 62 of 331 days2017: Unhealthy for Sensitive Groups 4 of 331 days2017: Unhealthy 3 of 331 days2017: Very Unhealthy 1 of 331 days20172018: Good 300 of 360 days2018: Moderate 53 of 360 days2018: Unhealthy for Sensitive Groups 5 of 360 days2018: Unhealthy 2 of 360 days2019: Good 288 of 333 days2019: Moderate 45 of 333 days20192020: Good 313 of 336 days2020: Moderate 15 of 336 days2020: Unhealthy 5 of 336 days2020: Very Unhealthy 3 of 336 days2021: Good 297 of 320 days2021: Moderate 23 of 320 days20212022: Good 269 of 328 days2022: Moderate 56 of 328 days2022: Unhealthy 3 of 328 days2023: Good 270 of 307 days2023: Moderate 32 of 307 days2023: Unhealthy for Sensitive Groups 2 of 307 days2023: Very Unhealthy 3 of 307 days20232024: Good 313 of 347 days2024: Moderate 34 of 347 days2025: Good 312 of 360 days2025: Moderate 46 of 360 days2025: Unhealthy for Sensitive Groups 2 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 year0501002003: 90th percentile AQI 542004: 90th percentile AQI 562005: 90th percentile AQI 522006: 90th percentile AQI 542007: 90th percentile AQI 562008: 90th percentile AQI 562009: 90th percentile AQI 522010: 90th percentile AQI 492011: 90th percentile AQI 522012: 90th percentile AQI 542013: 90th percentile AQI 592014: 90th percentile AQI 522015: 90th percentile AQI 552016: 90th percentile AQI 352017: 90th percentile AQI 582018: 90th percentile AQI 572019: 90th percentile AQI 532020: 90th percentile AQI 462021: 90th percentile AQI 452022: 90th percentile AQI 552023: 90th percentile AQI 522024: 90th percentile AQI 502025: 90th percentile AQI 522003: Median AQI 292004: Median AQI 312005: Median AQI 262006: Median AQI 272007: Median AQI 282008: Median AQI 292009: Median AQI 292010: Median AQI 272011: Median AQI 252012: Median AQI 252013: Median AQI 312014: Median AQI 252015: Median AQI 272016: Median AQI 182017: Median AQI 262018: Median AQI 232019: Median AQI 212020: Median AQI 182021: Median AQI 212022: Median AQI 232023: Median AQI 262024: Median AQI 202025: Median AQI 23200320052007200920112013201520172019202120232025
  • 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
Fine particles (PM2.5)360100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253603124620002352109PM2.5
2024347313340000205075PM2.5
20233072703220302652255PM2.5
20223282695603002355170PM2.5
2021320297230000214584PM2.5
20203363131505301846284PM2.5
2019333288450000215374PM2.5
20183603005352002357182PM2.5
20173312616243102658206PM2.5
2016332318140000183581PM2.5
20153593005630002755139PM2.5
2014311272390000255283PM2.5
2013333259740000315984PM2.5
20123593104810002554104PM2.5
2011363321420000255281PM2.5
2010365330350000274976PM2.5
2009365323420000295265PM2.5
2008366308580000295674PM2.5
2007363296670000285671PM2.5
2006351302490000275491PM2.5
2005365318470000265275PM2.5
2004366296700000315680PM2.5
20033492935600002954100PM2.5

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 Washington with a similar median AQI in 2025

All monitored counties in Washington

Source: U.S. EPA AirData, “Annual AQI by County” files for 2003–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem