I agree with you that the very idea that it is somehow acceptable to have an 'exhaust' on a car that just belches out toxins is just as crazy as dumping your nightpot out the top floor window into the middle of the street. There was also a time in which that was deemed 'normal'.

That said, a very large part of small particle dust produced by cars comes from wear, especially brakes, tires, road surface and crushed stuff by the weight of the car driving over. If there is a significant uptick in traffic, electric will be better than the equivalent traffic if it were all diesel, but the aggregate amount of micro dust might still go up compared to today's volume.