Smoke from the 2015 Canyon Creek wildfire in Douglas County, Oregon (Courtesy/Oregon Department of Forestry)

Unhealthy air conditions caused by wildfire smoke are on the rise across Oregon, even in urban areas located far from burning fires.

That's the conclusion of a Department of Environmental Quality report released recently, which looked at the number of days where air quality was unhealthy for sensitive groups or worse between July and September.

Air quality is determined by the amount of fine particulate matter in the air. It's one of the main pollutants released by burning forests.

The Salem area has fared better than many corners of Oregon, but still seen an increase in poor air quality. Last summer, four days were unhealthy for sensitive groups because of wildfire smoke, the highest number since at least 2000.

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Southern Oregon cities like Medford and Klamath Falls have seen the sharpest increase in wildfire-related air pollution. Last summer, those cities had 33 and 38 poor air quality days because of smoke. Portland had six, and Bend eight.

Graphic by Anna CK Smith/Salem Reporter

On days when smoke makes air unhealthy, the average air quality is worse now than it was several years ago, particularly in southern Oregon. Days when air is "very unhealthy" or "hazardous" have risen since 2012.

"There (have) been much more frequent impacts at a more “unhealthy” level," the report says. "If these trends continue, Oregon should expect to see an increasing number of unhealthy for sensitive groups or worse days during the summer, not just in Southern Oregon but also across the state."

Current air quality data is available on the department's website or via the OregonAir app.

Read our previous coverage:

Movement is slow to improve Oregon's response to wildfires

Federal climate change report says more wildfires, droughts and extreme weather in store for Oregon

Correction: The graphic in this article originally misspelled Klamath Falls.

Have a story idea? Reporter Rachel Alexander: rachel@salemreporter.com or 503-575-1241.