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How Smog Could Be Making Our Forest Fires Worse

Dead trees in the Sierra Nevada have become a wildfire issue. (Courtesy USDA Forest Service Region 5)
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Back in 1953, high up in the San Bernardino Mountains, foresters noticed something strange. The needles of ponderosa pines were yellowing and dropping, growth was slowing, and some were dying. They called the condition "X-disease" at the time, but soon figured out that it had to do with Southern California's notoriously toxic air.

In the decades since then, we've made big strides in tackling our air pollution problems, but both Southern and Central California still regularly violate federal air quality standards for ozone, roughly a third of the year.

So, it should come as no surprise that trees in some of our favorite places -- from the San Bernardino mountains to the southwestern part of the Sierra Nevada -- are still getting sick. Being made more vulnerable to life ending conditions, including those brought on by climate change. And in turn, becoming fuel for fires.


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