Usually by this time in October we’re thinking about rain, Halloween, and all things fall. We’re certainly not discussing wildfire smoke (or the Mariners!). Wildfire smoke impacts in Washington State usually occur in August and September. Average statewide fine particle (PM2.5) concentrations since 2000 agree with this assessment—and this year we are observing higher than usual PM2.5 concentrations in October. The figure below shows daily average PM2.5 data for all statewide monitoring sites since 2000, with the years 2000-2021 in grey and 2022 highlighted by the red trace.
Phil’s annual accumulation plots posted the other day are a great illustration of the cumulative exposure to PM2.5 throughout the year. Looking at average statewide PM2.5 concentrations, while 2022 is gradually increasing in exposure thanks to the past few weeks, the cumulative average PM2.5 concentration is less than recent years with larger fires or smoke that blanketed the entire state for weeks (i.e., 2017, 2018, and 2020).
And what about different regions in 2022? Smoke impacts started later in the year for most of the state with minimal impacts before September, and Central Washington has seen the worst of the smoke thanks to its proximity to the most active fires.
Looking at a few Central Washington air quality monitoring sites that have been most impacted this season, these graphics are a great tool to visualize how wildfire smoke over the course of a few weeks impacts the total PM2.5 exposure. The horizontal red line on each panel is the annual National Ambient Air Quality Standard for PM2.5 (we want to be well below this line!), and each point is the daily average colored by its respective AQI category.
Unfortunately, impacts from active fires in the Cascades continue in the Methow, Wenatchee, and western mountain valleys. The Puget Sound may also be impacted by wildfire smoke starting tomorrow. Check back here for more information and be sure to take a look at DOH's answers to questions about health impacts of wildfire smoke.