Thick, choking plumes of smoke from Canadas wildfires are pouring into major cities across the Midwest, Northeast and Mid-Atlantic, bringing dangerous air quality to more than 100 million people. The polluted air will last through at least Saturday in some areas as new waves of smoke waft south.

Here’s the latest:

• Choking air pollution: More than 100 million people in 18 states and the District of Columbia are under Air Quality Alerts, many of which note that the air pollution is so high, even healthy adults will be affected. “The risk of health effects is increased for everyone,” the Washington, DC, air quality council said in its alert.

• Where is it going? The smoke is being carried south from Canada in the wind. On Friday, the plume pushed farther south, making the DC area the new East Coast-epicenter of air pollution. The weather patterns will determine which parts of the US have the worst smoke each day.

• Relief is coming: Poor air quality is likely to be an issue through Saturday as the wind pushes the smoke back into the Northeast. But rain and storms are in the forecast, which will help wash the smoke out of the air and provide some relief.