Bringing in electric buses will not decrease these pollutants. They will also not remove enough of the other half of the pollutants. The change needs to be far wider and harsher.
On urban buses, which are constantly starting and stopping, I imagine it could be even more.
No brake pads required. Simply dump the energy into the battery (or a big heater for the excess when the battery is full or too cold to charge)
Obviously, you can't have a failure in the electrical or control system or you can't brake anymore, so that part will have to be designed with much more redundancy than it is in todays vehicles.
"In urban environments, brake wear can contribute up to 55 % by mass to total non-exhaust traffic-related PM10 emissions" [1]. (The "abrasion processes which result in direct particulate matter (PM) emission are tyre, brake, clutch and road surface wear, with other potential sources being engine wear, abrasion of wheel bearings and corrosion of other vehicle components, street furniture and crash barriers.")
When a vehicle regeneratively brakes, the brakes aren't engaged. Instead, the transmission connects to a generator, which resists the vehicle's motion as it converts kinetic energy into electricity.
It's true that there will be an increase in road / tyre dust due to the extra weight of batteries, but I'd be very surprised if this was as much as was saved elsewhere.