Canadian Wildfire Smoke Spreads, Puts More Cities at Risk.

Smoke from Canadian wildfires has spread south, causing hazardous air quality levels in several US cities. While New York and Washington DC have seen some relief, southern metropolitan cities such as St Louis and Louisville are forecast to experience unhealthy air quality. Over 400 wildfires continue to rage in Canada, with more than 200 considered out of control. Officials have urged residents to avoid going outside and to wear masks when venturing outdoors. Climate change increases the risk of hot, dry weather that fuels wildfires.