Dense smoke from forest fires burning in British Columbia and Alberta was observed at Ennadai Lake, Nunavut. The smoke travelled over Ontario and into Ohio and as far as New York. Known as “the Great Smoke Pall,” the plume disrupted flights, created blackout conditions in Sarnia, Ont., and caused the street lamps to be turned on midday in Toronto. Some concerned citizens thought the brown clouds were the result of a nuclear attack.