(The Conversation) – Canada’s seemingly endless wildfires in 2023 introduced millions of people across North America to the health hazards of wildfire smoke. While Western states have contended with smoky fire seasons for years, the air quality alerts across the U.S. Midwest and Northeast this summer reached levels never seen there before. The smoke left the air so unhealthy in Philadelphia on June 7, 2023, that the Phillies-Detroit Tigers Major League Baseball game was postponed.