Comment by tialaramex

All the cities you listed end up using the common EU standards for deciding emissions requirements, they just draw a different line as to what is allowed and from when. So maybe in one European city you need at least Euro 4 Petrol since 2024 and in another it was Euro 3 by 2025, but all you need to know as an owner or driver is that you're driving say a Euro 6 Petrol car or that the second hand car you just bought your teenage daughter is only Euro 4.

France has a layer where they translate from the Euro standards to their own system, but that's no different from having to mentally translate temperature units or distances.