Exposure to PM_2.5 pollution causes a number of adverse health impacts, particularly to the pulmonary and cardiovascular systems. Its impacts are especially harmful for those with chronic heart and lung diseases such as asthma, bronchitis, and emphysema. PM_2.5 exposure can exacerbate these conditions, which can lead to hospitalization or premature mortality. Sensitive populations, such as children and the elderly, also face greater risks of health impacts from PM_2.5 exposure. 

• In summer 2023, western Washington experienced brief and moderate periods of wildfire smoke. Wildfire smoke conditions were not severe enough to cause the year's 98th percentile PM_2.5 concentrations in any county to exceed Washington's healthy air goal of 20 μg/m³ based on summer concentrations alone. Three counties exceeded the healthy air goal in 2023: King, Pierce, and Snohomish. In all three counties, elevated concentrations were driven by a combination of moderate wildfire smoke impacts in summer and smoke from residential wood combustion during wintertime stagnation events. As King County comprises approximately 43% of the total population of the Puget Sound counties, the indicator results in 2023 are primarily driven by the inclusion of King County as an impacted county. However, only three of King County's nine monitoring sites exceeded the healthy air goal.

• In 2022, smoke from several fires in Washington’s Cascade Range caused intermittent periods of impaired air quality across the state, with an unusually late and severe smoke episode in western Washington in October. PM_2.5 monitors in Clallam, King, Mason, Pierce, Skagit, Snohomish, and Whatcom counties recorded 98th percentile concentrations above the Washington healthy air goal of 20 μg/m³. All monitors representing Island, Jefferson, Kitsap, San Juan, and Thurston counties met the healthy air goal.

• In 2021, western Washington experienced a relatively mild wildfire smoke season with only a few summer days with smoke impacts at most monitoring sites. Only three Puget Sound communities recorded a 98th percentile PM_2.5 concentration over Washington's healthy air goal of 20 μg/m³: Darrington, Marysville, and South Tacoma. Exceedances of Washington's health air goal were primarily observed during brief episodes of cold and stagnant weather in the winter months. During such conditions, residential wood combustion is a leading source of PM_2.5 in these communities.

• In 2020, greater than 99% of the Puget Sound population was exposed to impaired air quality. An extensive and severe wildfire smoke episode in late summer caused unhealthy air quality across the state, with many areas reaching the very unhealthy and hazardous ranges of PM_2.5 for several days. All but one monitoring site in the Puget Sound watershed (Neah Bay) recorded 98th percentile PM_2.5 concentrations above Washington's healthy air goal of 20 μg/m³. During this smoke event, many monitoring sites set records for their highest concentrations ever recorded. Outside of the wildfire season, PM_2.5 concentrations were relatively low.

• After two consecutive years of prolonged wildfire smoke impacts in 2017 and 2018, calendar year 2019 was marked by a mild wildfire season with very few smoke-impacted days. The exceedances of Washington's healthy air goal of 20 μg/m³ were primarily observed during brief episodes of cold and stagnant weather in the winter months. These episodes occurred with moderate frequency relative to other years. Residential wood combustion is a dominant source of PM_2.5 during cold, stagnant weather.

• In 2017 and 2018, smoke from local and regional wildland fires caused impaired air quality across western Washington for several weeks. The wildfire smoke incidents were so extensive and prolonged that they caused PM_2.5 concentrations to rise above Washington's healthy air goal of 20 μg/m³ for an extended period at most monitoring sites in the Puget Sound region. Consequently, the majority of Puget Sound residents were exposed to air quality that did not meet the state's healthy air goal for PM_2.5 in both years.

Future work on this indicator will attempt to develop a complementary measure of air quality that examines trends among environmental justice communities and/or tribal reservations. Identifying whether specific demographic groups are more exposed to poor air quality than others will help provide a more complete understanding of environmental and public health issues experienced across Puget Sound.

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The Washington Department of Ecology conducts a number of programs to reduce particle pollution in Washington. 

For more information about air quality monitoring in Washington, see the Department of Ecology's Air Quality Monitoring Network webpage and map of current air quality conditions. 

EPA's AirNow Fire and Smoke map displays agency PM_2.5 air monitoring data along with publicly available air sensor data calibrated using a national correction equation.

Department of Ecology (2009) Health Effects and Economic Impacts of Fine Particle Pollution in Washington