Bad Air Days in San Juan County, Washington
Not enough data
EPA monitors in San Juan County ran on too few days between 2016 and 2025 to give a fair yearly count (about 31% of days covered). Neighbouring counties below are a better guide.
What actually helps here
- EPA monitors here ran too few days to give a fair yearly count. Use AirNow for today's air.
The record for San Juan
| Date | AQI | Main pollutant |
|---|---|---|
| 2019-01-31 | 52 | PM2.5 |
| 2019-05-28 | 45 | PM2.5 |
| 2019-05-27 | 40 | PM2.5 |
| 2019-03-10 | 39 | PM2.5 |
| 2019-02-01 | 38 | PM2.5 |
An ordinary day in San Juan
Across 112 monitored days from 2019 to 2019, the air in San Juan County rated Good on 99% of them, more often than the 72% typical of monitored counties, and Moderate on 1%. The median day sat at AQI 21; one day in ten went above 31.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)100%112 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2019 | 112 | 111 | 1 | 0 | 0 | 21 | 52 |
Washington compared
- Yakima County13/yr
- Chelan County11/yr
- Okanogan County11/yr
- Stevens County9/yr
- Asotin County8/yr
- King County8/yr
- Snohomish County7/yr
- Benton County6/yr
How this is counted
A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.