There are loads of new temporary vignette zones, including Savoie and Haute Savoie so if we get a sticky high pressure like last year when air quality down in the valleys was awful then most likely they’ll be invoked – click through the links in this site to see the maps, but basically it’s all of the northern French Alps – PDS, Bourg St Maurice Val T etc https://www.crit-air.fr/en.html
The new environmental zone ZPA of Haute-Savoie
In October 2017, the entire department of Haute-Savoie with Annecy as its prefecture, announced the settlement of an air protection zone. In case of air pollution peak, the prefect is now able to make the Crit’Air badge mandatory and exclude the Crit’Air categories 4 and 5 from traffic …
Doesn’t mean you can’t drive in the areas, but depending on how bad the pollution is, they’ll restrict the worst polluting vehicles and those with no vignette!
There’s also some talk of the Grenoble fixed zone including the motorway that you’d use to get to some of the southern resorts such as Val D’Isere (rather than it just being a city congestion thing like London) – won’t really effect me, so not looked into that side of it. Lengthy discussion over on Snowheads.