As someone with allergies it is important to know each airline’s policies when travelling.
Many of them have detailed policies, and this chart lists the policies of 13 major carriers, including Air Canada.
Most airlines have detailed precautionary measures and emergency protocol they take for all kinds of other allergies, too. Allergic Living researched and put together a list of the allergy policies of 13 major airlines.
Here is a link to this well-researched article by Allergic Living.