you’ll be able to breathe 50 minutes of taxi air, but after you get out of that taxi the virus is still embedded in the mask, and kept moist by your respiration. With a wellfitted mask, there is a drag on inhale. You will breath a bit heavier, which can suck that mask virus, which is only trapped in the middle layer, into your breath. (the outer layer being waterproofing, the inner layer being absorbent, with the middle layer as the trap layer). Maybe it would be a good idea to carry several masks and ziplocks so you can take off the mask you wore on the bus or subway or other crowded environ, stick it on the dash of the car or windowsill to bake in the sun, and put on a clean mask? Plenty of videos of poor Chinese villagers who had only been given one mask, and had been wearing it for a week or more, rather than be beaten. Concentrating virus every day.
bkmk
When you get out of that taxi, you’ll be covered head to toe with the virus.