Wildfire smoke has been an unwelcome guest in Puget Sound the past two summers, with acrid, yellow smoke polluting the air and clogging lungs. Warnings about the health risks have been issued. Seattle is setting up filtered air "breathing rooms." Mayor Jenny Durkan has declared that Seattle be "Smoke Ready" as residents are told to expect more smoke, more frequently as the climate warms and Northwest summers get hotter and drier. But wildfire smoke is not a new thing. Indigenous people throughout the Northwest used fire as a tool for hunting and agriculture. Tribes used seasonal burning to promote edible plants like camas and huckleberries to create open prairies for hunting game and to encourage the growth of oak trees.