Erin Cotton didn’t notice the smoke until her eyes started to water and her two children complained they felt itchy.

“That’s when I remembered what I felt like during the Palisades Fire,” said Cotton, a Washington, DC, mother of a 5- and 1-year-old who lived in California as one of the most destructive wildfires in state history raged last year.

Cotton is one of more than 100 million people across the Midwest, Northeast and mid-Atlantic breathing in dangerous air brought by thick, choking plumes of smoke from wildfires in Canada.

Smoke put a damper on outdoor summer events across over a dozen states under air quality alerts. Events ranging from a baby parade in Flint, Michigan, to a rock concert in Herndon, Virginia, and the America’s Mile marathon in Pittsburgh were canceled Friday as smoke lingered. Businesses have also suffered during a busy season: Amusement parks like Kennywood and Sandcastle Water Park in Pennsylvania were shuttered due to the poor air quality.

Highly anticipated sporting events like the Cleveland Guardians game against the Pittsburgh Pirates and the RowFest National Championships in Michigan were called off or postponed.