Canadian wildfire smoke chokes Upper Midwest for second straight year

Smoke from Canadian wildfires has prompted health warnings across the Upper Midwest for a second straight year. Smoke from fires burning in British Columbia and Alberta have settled over parts of Montana, the Dakotas, Minnesota and Wisconsin. The Minnesota Pollution Control Agency issued its first statewide air quality alert of the season. Wisconsin also warned of unhealthy air pollution levels until noon on Monday. The National Weather Service said smoke could reach as far south as Iowa and Chicago by late Tuesday. Nearly 90 fires are burning in Canada, and prevailing winds are driving it south and east.