That’s because brakes are made from asbestos and every time you hit the break, they wear down. I work on old buildings and people always comment about working around asbestos but the people standing on street corners are exposed to far more than I am on a day to day basis.
Tires are bad too, polluting waterways with Zinc and a hundred other chemicals, like 6PPD. At least EVs and hybrids brake a lot less, but that still leaves more tire dust from the extra weight.