Tens of millions under air quality warnings as fires burn

Tens of millions of people in North America are experiencing dangerous air quality levels as intense wildfires burn across Canada.
Smoke blanketed large areas of Ontario and Quebec, while an orange haze hung over much of the north-eastern US throughout Tuesday and into Wednesday.
Toronto and New York briefly ranked among the metro areas with the worst air quality in the world overnight.
Much of the smoke is coming from Quebec, where 160 fires are burning.