Recent Canadian wildfires are record-breaking – and will threaten US air quality for days

Smoke rises from the Caribou Lake fire in an aerial photograph north-west of Cold Lake, Alberta, Canada, on 28 May. Photograph: Alberta Wildfire/Reuters

Enormous early-season wildfires have erupted across the prairie provinces of Canada this week, taxing local emergency response and threatening a long stretch of dangerous air quality across eastern North America.

The country’s largest fires – the Bird River fire and the Border fire – remain completely uncontained in northern Manitoba. In Manitoba alone, wildfires have burned about 200,000 hectares already this year – already about three times the recent full-year average for the province.