Wildfires are making the US smoggy, reversing progress on cleaner air, study finds

For more than a decade, the United States dramatically reduced its national smog levels, but since 2015 smoke from increasingly larger wildfires is reversing that clean-up trend and making the air dirtier and deadlier, a new study finds. Scientists say climate change deserves much, but not all, of the blame. Watch NBC Bay Area News free wherever you are WATCH HERE The national smog level dropped by 11% from 2003 to 2015 as strict federal regulations on power plants, cars and diesel engines kicke