Levels of air quality in Philadelphia were in the red Wednesday night, the worst of any major city in the U.S. and among the worst in the world as smoke from Canadian wildfires blanketed the area. Air quality alerts ranged from “Code Red” to “Code Maroon,” the most hazardous level you can get, and by 11:15 p.m., according to CBS News Meteorologist Andrew Kozak, the city was plunged into the worst air quality index in the country. After midnight the levels were still high; readings from AirNow showed just how toxic the smoke had become in Pennsylvania with the Susquehanna Valley (484), Philadelphia (425), and the Lehigh Valley taking up the top 3 spots for the worst air quality. The higher the number in air quality indexes, the more unhealthy and dangerous it becomes. But it’s not just Pennsylvania that’s suffering. Jersey City, New Jersey, and New Haven, Connecticut, were among those to have air quality indexes ranging from 200 to 300. More than 75 million people in the eastern U.S. were under air quality alerts Wednesday, with the smoke expected to worsen in New York City and surrounding areas on Thursday.