Canadian Wildfires Cause Hazardous Air Quality Alerts and Reduced Visibility in US.

Smoke from Canadian wildfires is spreading south over much of the Midwest, Ohio Valley, Northeast and Mid-Atlantic, bringing milky-white skies and dangerous air pollution to the most populous corridor of the country. Fine particles contained within the smoke, hazardous to breathe, have prompted air quality alerts for tens of millions of people from Baltimore to Boston to Burlington, but measurements show bad air affecting even a larger area that includes Minneapolis and Washington, D.C. The exceptionally unusual smoke episode could be made worse as there is a heightened threat for new fires both in the Great Lakes and the Northeast.