Jefferson, Washington Air Quality
Jefferson County, Washington (WA)
↓ Improvingover 10 years
10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days). This area has seen measurable air quality improvement over the decade.
Air Quality Day Breakdown
Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).
Year-by-Year Data
| Year | Median AQI | 90th Pct | Max AQI | Good Days | Moderate | Unhealthy+ | Pollutant |
|---|---|---|---|---|---|---|---|
| 2023 | 21 | 39 | 88 | 336 | 14 | 0 | PM2.5 |
| 2022 | 21 | 41 | 90 | 327 | 22 | 0 | PM2.5 |
| 2021 | 20 | 32 | 79 | 352 | 6 | 0 | PM2.5 |
| 2020 | 23 | 43 | 232 | 321 | 11 | 8 | PM2.5 |
| 2019 | 26 | 42 | 57 | 344 | 21 | 0 | PM2.5 |
| 2018 | 25 | 48 | 184 | 327 | 26 | 6 | PM2.5 |
| 2017 | 24 | 51 | 108 | 328 | 36 | 1 | PM2.5 |
| 2016 | 24 | 39 | 65 | 336 | 12 | 0 | PM2.5 |
| 2015 | 26 | 51 | 75 | 275 | 32 | 0 | PM2.5 |
| 2014 | 27 | 52 | 68 | 302 | 40 | 0 | PM2.5 |
What This Means for Jefferson County Residents
Jefferson, Washington has received an Air Quality Grade of B (77/100) based on a decade of EPA monitoring data. The current median AQI of 21 falls in the "Good" range.
Encouragingly, air quality here has been improving, with the median AQI dropping by 6 points over the monitoring period. This trend suggests continued investment in emission controls and cleaner energy.
The primary pollutant affecting this area is Fine Particulate Matter (PM2.5). Over the past 5 years, this area has averaged 2 unhealthy air quality days per year — days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity.