Smoke from wildfires burning in three Canadian provinces covered about a third of the U.S. on Wednesday, forecasters said, but had little effect on air quality except in New England and parts of New York state and the Midwest.

More than 31,000 people were under evacuation across Canada on Wednesday as firefighters battled raging wildfires threatening towns and villages, authorities said.

The latest NOAA forecast models foresee smoke persisting in the skies over Philly through the day Wednesday and likely into Thursday. The combination of warmth and the smoke was forecast to drive ground-level ozone to hazardous levels in the afternoon. The region and other parts of the nation are under a “code orange” air-quality alert.

Parts of central Pennsylvania are under a code orange air quality alert, but the Midwest is seeing bigger air quality problems.

Ontario Premier Doug Ford is pressuring Canada’s Prime Minister Mark Carney to ramp up tariffs against the United States after President Trump doubled tariffs on steel and aluminum earlier this week.

Canada is preparing retaliatory measures as U.S. President Donald Trumps decision to double steel and aluminum tariffs to 50% took effect, impacting key trading partners like Canada and Mexico. Prime Minister Mark

Canada is going to wait before enacting any further retaliation against the U.S. over higher steel and aluminum tariffs because negotiators are in talks on a new bilateral economic-and-security deal,

Prime Minister Mark Carney said Canada won’t respond immediately to the Trump administration’s doubling of steel and aluminum tariffs, and indicated that officials are in “intensive discussions” about the trade relationship between the countries.

Prime Minister Mark Carney says Canada will take "some time" on its response to increased U.S. tariffs on steel and aluminum.