Prepare for More Smoky Summers in the Midwest and Northeast

By Aydali Campa

CHICAGO—Parks, beaches and restaurants offering outdoor dining are typically booming here in the summer months after a long, frigid winter, but smoky skies have kept many residents indoors since Tuesday when Chicago’s air quality was briefly the worst in the world.

Smoke from wildfires in Canada has blanketed parts of the Midwest and Great Lakes this week, with the highest particulate matter levels in parts of Illinois, Wisconsin, Michigan, Pennsylvania and Iowa, according to air quality tracking by the Environmental Protection Agency. PM2.5, particulate matter smaller than 2.5 microns—about 30 times smaller than the diameter of a human hair—is a mixture of solid and liquid particles in the air that can harm human health when inhaled.