ST. PAUL — The Minnesota Pollution Control Agency has issued an air-quality alert for the northern half of Minnesota from 4 a.m. to 4 p.m. Tuesday, May 16. Wildfires in western Canada are sending smoke east and noticeable haze will be seen across the region Tuesday. A cold front is expected to sweep across the state Tuesday and bring the smoke with it, with sinking air behind the front bringing the smoke to ground level. The alert includes all of the state roughly north of a line from Ortonville, along the South Dakota border, to Pine City, in Pine County. People in the affected area may see and smell smoke even though the fires are far away.