Seattle air quality exceeded the WHO annual limits on about 1/6 of days from 2020 to 2021. Seattle air quality averaged nearly over 18 times the daily recommended limit of dangerous PM2.5 pollutants on its worse day in 2020. Seattle’s air quality worsened to these dangerous levels largely due to wildfires on the west coast bringing wildfire smoke to the area.
Current Air Quality in Seattle
16% Of Days in Seattle More Polluted Than WHO Target
Seattle’s daily air quality levels exceeded the World Health Organization (WHO) annual limit on 16% of days from 2020-2021. Some days in Seattle saw air pollution levels reaching “very unhealthy” levels, far above safe levels. Again, this was largely due to the wildfires in September of 2020.
Historical Air Quality Readings for Seattle
Is Seattle Air Quality Improving?
In the last three years, data shows little improvement in Seattle air quality. Air quality in 2020 worsened by 25% from 2019. 2021 levels have improved compared to the past two years so far, but wildfire season is still in progress.
Why Is the Air Quality Bad Today in Seattle?
Weather plays a big role in how the air quality is in Seattle each day. The amount of sun can affect how much ozone there is, and wind and rain can affect PM2.5 and particulate air pollution to varying degrees.
Air pollution levels can change quickly, with levels often varying widely throughout the day. Data shows there even appears to be times of the day where air pollution tends to be lower compared to other times.
Below shows how PM2.5 air quality levels around the world tend to vary throughout the day. PM2.5 levels have a tendency to be slightly lower in the afternoon compared to other times of the day. But this is a general trend, Seattle PM2.5 AQI levels will not follow this trend every day.
How California Wildfires Affect Seattle Air Pollution Levels
Outside of weather, wildfires are another factor that can significantly affect Seattle air. The worst wildfires typically occur in the months of June to September.
Read More: How Wildfires in California Affect Air Pollution Levels
Below shows how wildfires in September of 2020 affected air quality levels all across the west coast.
Seattle Air Pollution: The Negative Health Effects
This analysis of Seattle’s air quality is based on PM2.5 pollution. These are particles smaller than 2.5 microns in diameter that can penetrate deep into the lungs and even enter the bloodstream.
Studies have shown that PM2.5 raises blood pressure, inflammation, and rates of heart attacks and strokes.
WATCH: Why Is PM2.5 So Harmful to Us?
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Protect Your Health in Seattle
Despite the harms of PM2.5, placebo-controlled studies of air purifiers have found that removing particulate in the home has positive effects on blood pressure, inflammation, and immune response.
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