In certain parts of the United States, people have been affected by wildfires and the resulting smoke for years, dealing with air quality warnings and orange, dusty skies on a semi-regular basis. But this year, wildfires burning in Canada have put other regions at risk, and apocalyptic-looking skies have prompted fresh questions for those unfamiliar with wildfires and their effects: Should I wear a mask outside? Can I leave my windows open? Do I need to clean my air filters?