The Public Health Agency of Canada says it is "aware of the situation" and looking into it.
Many said they didn't experience any extra measures when returning to Canada.
They're looking for other passengers of a China Southern Airlines flight.
Canada's best airport was Edmonton's.
The incident didn't affect airport operations, however.
The incidents could have been catastrophic.
One of the planes caught fire.
Officials have asked people to check their flights before heading to the airport.
The company called a Friday delay at Canada's largest airport a hiccup.
Passengers on the flight set to travel to Chicago experienced long delays.