Driving or exercising with a mask, especially if N95, is a mistake. I recall seeing quite a few references showing lower oxygen levels on a person with a mask. That and a few lethal accidents where the driver passed out while wearing a mask.
It is summer here and the use of a mask outside is very noticeable. For the delivery drivers and their open trucks (no AC), I think it would be a very dangerous combination.
This has be debunked about 1000 times.
The videos people are putting up to show it depletes oxygen levels are measuring the exhaled air.
If your air goes in at 20% O2 and comes back out at 20% O2 you are... well... dead.
Thus it is perfectly normal for air to go in at 20% O2 and come back out at around 18.5% O2.
Even the concentration of air trapped behind the mask rising in CO2 concentration and dropping in O2 concentration is a bit dumb to consider. You breath well over a litre of air each breath, the handful of cm3 of air behind the mask will not cause any issues.
Go and watch the dozens of videos of doctors, nurses and fitness specialists testing this with Blood O2 saturation meters on people, themselves and on athelites on tread mills wearing masks.