Wildfires are making extreme air pollution even worse in the northwest U.S.
Smoke from blazes ravaging western states is counteracting clean air improvements
![wildfire](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2018/07/071318_LH_wildfire-air_feat_REV.jpg?fit=860%2C460&ssl=1)
BAD BURN Wildfires such as this one, which burned almost 50,000 acres in Oregon and Washington in 2017, are one reason why the days with the worst air quality are becoming even worse in the northwestern United States.
Brian Tai/U.S. Forest Service (Public Domain Mark 1.0)