Canada wildfires: Millions advised to mask up due to intense smoke

Millions of people in North America have been advised to wear N95 masks outdoors due to poor air quality levels sparked by intense wildfires in Canada.

New York will begin distributing free masks on Thursday. Canada has said that people should wear a mask if they are unable to remain indoors.

The smog is expected to spread beyond New York to other East Coast areas.

Officials warn that the dangerously smoky conditions are expected to persist into the weekend.

People in several cities across the US woke up on Thursday to hazardous air quality conditions, including in Philadelphia and other parts of Pennsylvania. Other parts of the US, including large swaths of the Midwest and the South, are also under air quality alerts.

Much of the smoke is coming from Quebec, where 150 fires are burning. It is already Quebec's worst fire season on record.