In Northern California, more than 17,000 firefighters continue to fight over a thousand wildfires. The blazes have scorched more than 550 square miles and destroyed more than fifty buildings. Air pollution warnings have been issued throughout Northern California. Officials say air pollution readings in the region are two to ten times the federal standard. Some areas are experiencing the worst air quality on record, with the smoke hanging down to the ground like a fog. The fires have destroyed nearly fifty structures, injured eighty-five people, and threaten nearly 10,000 homes.