To answer this question (which is different from asking "Which mask?") you have to define what "pollution" means and then examine the available masks to see if they do anything to reduce it.
Just offhand, I believe that "pollution", in an urban traffic setting, consists of carbon dioxide, carbon monoxide, sulfur dioxide (and various other sulfur compounds), nitric/nitrous oxide (and various other nitrogen compounds), and soot (which contains a significant amount of unburned hydrocarbons). (Lead used to be a significant component of exhaust but is no longer, with unleaded gasoline.) Of these, only the soot is really "visible", while the sulfur and nitrogen compounds can contribute to "yellow haze".
A simple filter mask will remove only the soot (if that). You need a mask containing at least a reasonable layer of activated charcoal (ie, a canister) to remove much of the others. The masks I see advertised just have a thin layer of "activated charcoal cloth" or some such, not enough to make a noticeable difference.
I was unable to find any evidence of rigorous testing of these masks anywhere -- by the manufacturers or independent bodies. They do test for particulate filtering, but that's of minimal value, and, besides, you can buy (much) cheaper particulate filters if you skip the "pollution" moniker.