In California, a fast-growing wildfire has scorched more than 65,000 acres in the Los Padres National Forest, with the flames fanned by dry, gusty winds. In Arizona, a wildfire on the North Rim of Grand Canyon National Park has become the largest active wildfire in the U.S. The Dragon Bravo Fire has consumed about 125,000 acres since it erupted on the Fourth of July. Meanwhile, vast swaths of Canada and the United States are experiencing unhealthy air quality due to wildfires raging across five Canadian provinces. Smoke from the fires has triggered air quality alerts for tens of millions of people in cities stretching from Minneapolis to Boston.