I'm planning a trip for a family member that will involve a Europe-US flight in AC business class connecting at YUL or YYZ (onward flight being AC metal or UA codeshare). The relative tends to get dried out from airplane air and therefore being able to step outside to get fresh air is helpful.

Does either airport have an outdoor terrace airside (either in a public area or an airline lounge) where it's possible to get some fresh air that someone connecting to a US-bound flight could access at any point?

Alternatively, how long of a layover is sufficient to go landside at either of these airports to get some fresh air?