Towering plumes of smoke fill the sky as firefighting helicopters battle fast-moving wildfires in western Canada. The massive blazes are sending smoke south, t

Towering plumes of smoke fill the sky as firefighting helicopters battle fast-moving wildfires in western Canada. The massive blazes are sending smoke south, triggering air quality alerts across more than a dozen U.S. states, including Washington, D.C., as officials warn millions about unhealthy ai…