[raxxorraxor]

Some argue that these coarse particles are less damaging for your health than the finer particles we are exposed to today, even if you cannot see them settling as dirt.

Although on that part tire abrasion is probably even a larger factor than exhaust particles, even if it doesn't smell as badly. Some say the factor is beyond 1000x for tire abrasions. Info is hard here, because many sources have their own ball in the game.

But cars today are significantly more heavy, which increases these abrasions nonlinearly.