Watch Clip
Millions warned to stay inside as smoke covers eastern U.S.
4m 15s
A heavy pall of polluted air still blankets much of the eastern U.S and it may not dissipate for days as fires in Canada send vast curtains of smoke south. The bad air has officials warning that breathing it can be hazardous to your health. It's also scrambling schedules from airports to schools to the White House. Stephanie Sy reports.