The panny-D was great for that, early days saw stuff like clean air in China, India, wildlife coming into the cities, clean water in Venice, etc - and that was after only a few weeks.

We've had car-free sundays in the past a few times, but that was also due to oil crises. But also, a lot of inner cities have a ban on cars, a restriction on cars (only locals and suppliers at fixed times), or environmental zones (no older Diesel engines, some are going a step further and banning all vans and trucks, promoting electric alternatives for last-mile deliveries). They're all having a significant impact on the health and liveability of city centers.

But it makes a lot of sense too, as they're 1000 year old city centers that were never designed for cars anyway. Often the only roads that can support cars at a normal in-city speed are on the outside of where city walls used to be.

Anyway, speaking for myself, I haven't used FB in forever, I don't think a blanket pause would affect most people that much, I posit it's only a small minority that falls into the problematic FB usage category.