More than 100 million people across the Midwest, Northeast and mid-Atlantic regions are facing hazardous air quality as smoke from wildfires in Canada spreads across large parts of the United States.

The thick smoke has disrupted daily routines, outdoor activities and major events, with residents reporting irritated eyes, breathing difficulties and hazy conditions. Some families have been reminded of previous wildfire disasters, while others have compared the widespread indoor restrictions and mask recommendations to the early days of the COVID-19 pandemic.

Outdoor events in more than a dozen states were canceled or postponed Friday because of dangerous air pollution. Events affected included a baby parade in Flint, Michigan, a rock concert in Herndon, Virginia, and the America’s Mile marathon in Pittsburgh. Several Pennsylvania amusement parks, including Kennywood and Sandcastle Water Park, also closed temporarily because of the poor air quality.

Sporting events were affected as well. The Cleveland Guardians' game against the Pittsburgh Pirates was postponed, while the RowFest National Championships in Michigan were also called off or delayed.

The smoke has also created uncertainty around the World Cup final scheduled for Sunday in New York City. Forecasts suggest the heaviest smoke could move away before the match, although lighter haze may remain in the region. Storms expected on Saturday could help clear the air before fresher conditions arrive.

For many residents, however, the smoke has already changed weekend plans. Some people have abandoned outdoor exercise, while others have canceled walks, family activities and trips to public spaces. Businesses that depend on the busy summer season have also faced losses as customers stay indoors and outdoor venues shut down.

Officials in several states have urged residents to remain indoors when possible and to wear well-fitted N95 or KN95 masks if they must go outside. Health departments in cities including Detroit, Philadelphia and Washington, DC, have distributed masks and warned residents about the risks of prolonged exposure to polluted air.

People with asthma and other respiratory conditions, outdoor workers and those experiencing homelessness are among the groups facing heightened risks. Health professionals expect some patients with breathing conditions to experience worsening symptoms as the smoke continues to affect communities.

The forecast offers some relief. A storm system is expected to bring rain and shifting winds, helping push the thickest smoke away from parts of the Northeast and mid-Atlantic. Although some haze could return Sunday, air quality is expected to improve compared with recent days.

Weather conditions for the World Cup final are expected to be generally favorable, with temperatures in the low 80s and skies likely to clear after Saturday's storms. However, lingering smoke could still leave some haze in the atmosphere.