Fleurpepper
Mamie
You need Crit'Air for zones around French towns. This is the official website. It costs under 5€ and lasts for the life of the car.
www.certificat-air.gouv.fr/
Only for a few towns though- and not necessary in most of France.
The Swiss vignette for 40 CHF is great value- and can be bought at the border crossing. This is not required for normal roads, only MWays- but as a tourist you will probably use MWays. Where will you be crossing into Switzerland, and where will you be visiting there?
Hmm I think that is changing Fleurpepper. I know of a few people caught out driving round Rouen, for example. Seriously, why would you not pay a few euros for a sticker that lasts for the lifetime of the car to be on the safe side?