Why is it so smoky? Canada wildfires spark air-quality alerts in north-east US

Hazy skies hung over north-eastern US a day after the midwest received a similar alert from the Environmental Protection Agency

Canada is dealing with a series of intense wildfires that have spread from the western provinces to Quebec, with hundreds of forest fires burning. Wind has carried smoke from the fires southward, triggering air-quality alerts throughout the United States.

The US Environmental Protection Agency (EPA) on Tuesday issued a poor air-quality alert for New England, a day after parts of Illinois, Wisconsin and Minnesota received a similar advisory. Last week, US officials as far south as Maryland, Virginia and Pennsylvania reported being affected by the wildfires.