Air quality alerts are in effect in the Philadelphia area, fueled by smoke from wildfires that are burning thousands of miles away.

Canada is battling more than 700 active wildfires across the country, roughly two-thirds of which are burning out of control, according to the Canadian Interagency Forest Fire Center (CIFFC). Smoke billowing from the blazes has blanketed central Canada and the northern U.S., prompting widespread air quality alerts.

Red flag warnings remain in place for parts of Nevada, Utah, Colorado and Wyoming due to very dry conditions, low humidity and gusty winds.