OTTAWA -- Canadians boarding a flight without a mask will now be forced to provide medical proof that they can’t wear one, a revised federal travel order states.

Non-medical masks have been mandatory on flights since April 20. But until last week passengers could say they have “breathing difficulties unrelated to COVID-19” as a reason for not wearing a mask. 

That’s no longer the case, under an updated Transport Canada order issued on Friday that states a medical certificate will need to be shown that shows the traveller is unable to wear a mask for a medical reason.

There remain exceptions for infants, as well as people who are unable to remove their face mask without assistance.

Under the order, a mask is defined as: “Any non-medical mask or face covering that is made of at least two layers of tightly woven material such as cotton or linen, is large enough to completely cover a person’s nose and mouth without gaping and can be secured to a person’s head with ties or ear loops.”

Other than going through security, wearing a mask is required when travelling through an airport as well as when on board an airplane.

The federal order mandating this has been updated and amended several times over the course of the pandemic. It’s under the same order that mandatory temperature checks were implemented.