Although plastic particles in the air are increasingly coming into focus, knowledge about their distribution and effects is still limited. Chemical analyses from Leipzig now provide details from Germany for the first time: Around 4% of the particulate matter consists of plastic. Around two-thirds of this comes from tire abrasion.
There was this chapter in an XKCD book talking about where does tire particles goes. From memory, it said “there are many answers to that question and none of them are good”.