Just a theory but I'm also 100% sure it's true

https://lemmy.curiana.net/post/450159

Sound is annoying but exhaust in general sucks. One thing that was amazing around april or may of 2020 was how clean the air smelt for a brief time.
2021 was a cyclist’s dream. Clean air and no cars
and everyone was instructed to give you at least 10 feet of distance :)

Australia, so 2m, but yeah

We were not allowed out except for a few exceptions, one of which was an hour a day of outdoor exercise

I would commute by bike to my preferred exercise location an hour away, ride for exercise for an hour, then commute by bike home again