Smoke from Canadian wildfires poured into the US East Coast and Midwest on Wednesday, covering the capitals of both nations in an unhealthy haze, sending school recesses indoors and prompting people to fish out pandemic-era face masks.

While Canadian officials expanded evacuation orders and asked other countries for help fighting more than 420 fires nationwide, air quality with what the US rates as “hazardous” levels of pollution extended into central New York, with massive tongues of “unhealthy” air extending as far as Virginia and Indiana.

In Baltimore, Maryland where officials warned residents to stay indoors when possible and limit outdoor exertion, Debbie Funk sported a blue surgical mask as she and husband Jack Hughes took their daily walk around Fort McHenry, a national monument overlooking the Patapsco River. The air hung thick over the water, obscuring the horizon as distant ships pushed slowly through the haze.

“I walked outside this morning and it was like a waft of smoke,” said Funk, who said the couple had considered skipping the walk but wanted some exercise. The two planned to stay inside later Wednesday.

Canada’s wildfire season started early this year and accelerated very quickly, exhausting firefighting resources across the country, Canadian Interagency Forest Fire Centre spokesperson Jennifer Kamau said.

Smoke from the blazes in various parts of the country has been lapping into the United States since last month, but intensified with a recent spate of fires in Quebec, where more than 100 fires were burning and considered out of control Tuesday.

The largest town in Northern Quebec — Chibougamau, estimated population 7,500 — was evacuated Tuesday, after another Quebec community was left to burn Monday, drawing the ire of local residents.

Quebec Premier François Legault said Monday that authorities had no choice because the fire around the hamlet of Clova was too intense to send in water bombers. That remained true Tuesday, he said, but he noted that no homes had actually burned.

Kamau said more than 950 firefighters and other personnel have already arrived from the US, Australia, New Zealand and South Africa, and crews from Costa Rica will be arriving soon.

Across the border, the effects of the blazes blotted out skylines and irritated throats.

“It’s sunny, but there’s no sun,” Michele Kluk said as she emerged from a Target store in Mechanicsburg, Pennsylvania, with “a bunch” of allergy medication in response to the air quality.