BOISE, Idaho — The central mountains are shrouded in smoke and unhealthy air as wildfires continue to burn there. Even though valleys are seeing better air quality right now, the Treasure Valley had a significant stretch of poor air quality.
On July 23, the Treasure Valley experienced a first as the surface ozone reached the "very unhealthy" or purple category, according to the Idaho Department of Environmental Quality (DEQ).
The EPA considers surface ozone a pollutant and harmful to public health. Ozone and smaller particulates, like wildfire smoke, are tracked separately. Ozone is 10 micrometers, and wildfire smoke is smaller, 2.5 micrometers.
But even though they're tracked separately, their concentrations can sometimes influence each other.
Idaho DEQ Airshed Coordinator Mike Toole explained, "Ozone is not emitted from any source. It's actually a chemical reaction that occurs at ground level. You have to have the precursors, warm temperatures and usually direct sunlight.
"So, all these factors go into it. On that particular day, we had summertime conditions, hot temperatures, and depending on what is burning in these fires, (sage brush, trees, or grasses) it can change what type of pollutants are in that smoke. So when it's pushed into the Treasure Valley, it adds to help mix and create ozone to a higher level."
Toole also said the wildfire smoke impacts over the past two months are similar to what we saw in other busy fire years, 2021, 2017, and 2015
"Those three years compare very well based on the duration of the events and having elevated concentration," he said. "2020 and 2022 has similar durations of impacts, but the concentrations were much lower."
Toole elaborated local fire activity plays a big part in determining if we have high smoke concentrations for longer periods.
"[2024] has been somewhat unique, I wouldn't say an outlier, but we had the three Eastern Oregon fires right on our doorstep. And then after we got through that, we had the Paddock fire just north of Emmett, which was inside the door, if you wanted an analogy. They were just right there in the perfect location to inundate our area."
In general, fire season in the Gem State can last until October. So, we still have a few more months of fire potential.