https://www.independent.co.uk/news/science/pollution-microplastic-waste-tires-b2794350.html
"In recent times, tire wear particles have been found to account for about 45% of all microplastics in both terrestrial and aquatic systems."
"Researchers in 2020 found that more than half of the coho salmon returning to streams in Washington state died before spawning, largely because of 6PPD-Q, a chemical stemming from 6PPD, which is added to tires to help keep them from degrading."
The most frustrating thing about all this? Cities don't clear sidewalks, so more cars
That article in particular focuses on filtering out tire wear particles AFTER they've entered the environment. Which is very much a band-aid, and it filters them AFTER we've breathed in the airborne particles.
We can stop them from ever being released by designing cities not for cars, but we need actual political leadership for that. Limiting/removing cars also comes with a ridiculous number of other benefits, too. Truly too many to count!