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Air quality failed health standards five consecutive days; welcomed improvements today

View of Spokane with wildfire smoke

Spokanites, rejoice! Our county is finally getting some reprieve from the wildfire smoke that has plagued us for days. While air quality hasn’t returned to the “good” range yet, it is in “moderate” for now, which is a big improvement from the last five days.

Last Friday, September 9, was the first in string of five days that failed to meet the federal, health-based standard for fine particles (PM2.5).

Particles measuring 2.5 micrometers and smaller are referred to PM2.5. These microscopic particles come mostly from combustion-related activities. The health-based standard for PM2.5, established by the U.S. EPA over two decades ago, is a daily average, midnight-to-midnight, of 35 micrograms per cubic meter of air. This is equivalent to an Air Quality Index (AQI) of 100. Below is a summary of each day’s concentration and corresponding AQI.

DatePM 2.5 concentration (ug/m3)AQI / category
Friday, 9/941.3115/Unhealthy for Sensitive Groups
Saturday, 9/1044.0122/Unhealthy for Sensitive Groups
Sunday, 9/1168.8158/Unhealthy
Monday, 9/12103.5176/Unhealthy
Tuesday, 9/1363.2155/Unhealthy

Interested in historical comparison? Here is a chart of days when PM2.5 failed to meet air quality standards since 1999, including concentration, AQI and cause. Learn more about particle pollution.

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