Haze From Western Wildfires Spreads to East Coast , Prompting Health Warnings. Wildfire smoke from Canada and the Western United States stretched across North America this week. 'The New York Times' reports that the smoke created a thick haze and triggered health alerts from Toronto to Philadelphia. As of July 21, air quality remained in the unhealthy range across the East Coast. This week, the air quality index spiked across the Midwest and East Coast as a result of the fires. The index goes from 0 to 500. The bigger the number, the greater the level of air pollution. Readings over 100 are considered to be particularly unhealthy. Numbers reached as high as 160 in New York City, a range where sensitive groups and the general public may experience adverse health effects. According to CNN, cold fronts coming into the area may help residents breathe a little easier, . but the haze could keep returning until the fires diminish or the jet stream changes. Over 80 large wildfires are currently active across 13 states in America. Many more are burning across Canada