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Air Monitoring Filters Take a Hit During Wildfire Events

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Air Monitoring Filters Take a Hit During Wildfire Smoke Eventsair monitoring tech at air monitoring site

Have you ever wondered how Spokane Clean Air determines the Air Quality Index (AQI)? We operate a network of seven monitoring stations located throughout Spokane County. The monitors at these stations capture criteria air pollutants and help us determine pollution concentrations.

But what happens when there is a thick layer of smoke in the air?

Simply put, the filters in Spokane Clean Air’s three TEOM (tapered element oscillating microbalance) air monitors must be changed out much more frequently. And during the 2017 wildfire smoke events, Spokane Clean Air was busy changing out the filters every few days to ensure accurate readings.

“A new filter typically lasts anywhere from two to three months, depending on the conditions,” explained Mike McKay, Air Quality Technician at Spokane Clean Air. “Once the sample loading on a filter reaches 90% of the filter’s capacity, it is changed out to ensure that it does not reach 100% capacity. If a filter exceeds 100% capacity, the data could be considered invalid.” Because of this, Spokane Clean Air must diligently watch diagnostic reports during times of elevated air pollution. 

When air quality was at its poorest condition during the summer of 2017, one filter only lasted 10 days before reaching 89%. Basically, one day of heavy smoke was equal to about 10 days of normal particulates. And if you remember, we had many days with heavy smoke in the Spokane area.

Interestingly, Spokane Clean Air’s three newest samplers are BAMs (Beta Attenuation Monitors). These monitors use a filter tape that advances every hour – much like a 16mm film projector with two reels. The BAMs had no filter issues and did not require any special maintenance during even the heaviest of wildfire smoke. 

3104 E Augusta Ave, Spokane, WA 99207 · (509) 477-4727 · working with you for clean air

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