Wildfire Smoke Darkens Skies and Triggers Air Alerts in Northern U.S.

Haze from wildfire smoke blankets the Ben Franklin Bridge and Penn’s Landing in Philadelphia, June 7, 2023. Millions of people across North America on Wednesday faced another day of hazy skies and serious air pollution caused by smoke that had drifted down from Canadian wildfires a day earlier. (Todd Heisler/The New York Times)