That’s a great question. The “harmonization” rules aren’t a separate regulation but a series of revisions to whatever regulations set out the first aid requirements for that jurisdiction. In most provinces, that’s the OHS regulations. But there are exceptions. Example: In Ontario and BC, first aid regulations are part of the workers comp laws.
Harmonization applies to kits, equipment and training but not the numbers of first aiders required at particular workplaces. In other words, harmonization doesn’t change the basic rules for calculating numbers of first aiders needed based on numbers of workers, location and distance from a hospital and risk of the operations performed.
