OTTAWA -- Canadians boarding a flight without a mask will now be forced to provide medical proof that they can鈥檛 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 鈥渂reathing difficulties unrelated to COVID-19鈥 as a reason for not wearing a mask. 

That鈥檚 no longer the case, under 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: 鈥淎ny 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鈥檚 nose and mouth without gaping and can be secured to a person鈥檚 head with ties or ear loops.鈥

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鈥檚 under the same order that were implemented.