Winter Or Wildfires? See When Treasure Valley Air Is Most Polluted

Aug 24, 2015

See the interactive chart below.

The Idaho Department of Environmental Quality (DEQ) issued an alert Monday declaring air quality unhealthy again in the Treasure Valley. The agency issued a similar alert last Thursday.  

If your shortness of breath is giving you déjà vu, you’re not alone. This summer's smoke and wildfires are approaching the numbers put up in the summers of 2007, 2012 and 2013.

Last summer, we combed through DEQ data that compared air quality of the past seven years to gain insight into what average truly looks like when it comes to air quality in our region. Results showed only 1.6 percent of days recording orange-level air quality or worse. Those numbers put the severity of this week’s red-level alert into perspective.

Forecasters say the chance of the smoke clearing any time soon does not look good. 

The Stage 1 Air Quality Advisory issued last week by the DEQ is still in effect and prohibits all outdoor burning activities.

This story was originally published on August 26, 2014.

The Treasure Valley has seen a handful of wildfire-induced hazy days this summer, but it's been nothing like 2012 or 2013 when big wildfires around the region brought smoke into Boise and surrounding communities, settling in the valleys and making it hard to breathe.

During the last couple of summers, we asked Idaho’s Department of Environmental Quality (DEQ) how the air quality compared with previous years. The DEQ folks said they didn’t know. They had all the data, but no easy way to compare time periods.

So we got their data and here’s what we found.

In the last seven and a half years, the worst air quality measured in the Treasure Valley was in July 2007. That's where many of the red and purple stars are clustered in this interactive visual, that shows peak air quality.



Hover over each star for more information.

Like 2012 and 2013, 2007's smoke-filled air happened during wildfire season. The Murphy Complex burned more than 650,000 acres in southern Idaho and northern Nevada beginning in mid-July 2007. It’s one of Idaho’s biggest fires, making the National Interagency Fire Center’s list of historically significant fires.

However the Murphy Complex started after the Treasure Valley’s stretch of bad air quality began. Other wildfires were burning in the region during that time, including the Dry Creek fire near Grangeville.

Not only did July 2007 record the most bad air days, it had by far the worst single day: July 5. DEQ regional air shed manager Mike Toole says it’s common for air quality to be noticeably poorer the day after fireworks fill valley skies and streets.

Of course, bad and good are relative terms. What we’re talking about is Air Quality Index (AQI) numbers. Monitors around the valley take hourly readings of several pollutants. Add them together and you get the AQI number.

There’s also a color system that goes with the numbers. Green is good, yellow is moderate, orange is unhealthy for sensitive groups (USG) like people with respiratory problems, red is unhealthy, purple is very unhealthy and maroon is hazardous.

Of the nearly 3,000 Treasure Valley days represented in our interactive chart, 75 percent had good air. Another 23 percent were moderate. Just 1.6 percent of those days were orange or worse. The Treasure Valley's poorest air quality from 2007 through June 2014, was recorded in July 2007 and August/September 2012.

It’s not just summer wildfires that hurt air quality. The Treasure Valley is infamous for winter inversions. The worst in the seven year period we’re looking at was in January 2013. Six days hit the orange air quality category, meaning it was unhealthy for sensitive groups (USG).

A report that measures air quality in a different way, found Idaho's level of air pollution is increasing.

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