Smoke rises from a wildfire approaching Twisp, Wash., on Aug. 19. Smoke can damage the health of people hundreds of miles downwind.
Health departments across the West are mobilizing to protect residents from smoke generated by dozens of fires that have sent smoke as far east as the Midwest.
"It's really bad," says Janice Nolan, assistant vice president for national policy at the American Lung Association. "I hadn't seen 'code maroon' days, which is the most hazardous air quality, in years."