This is just one study and I’m not familiar with the journal it’s in, so this isn’t definite. File it under “intriguing possibility of another unintended consequence”.
A researcher says that because electric cars are heavier than their gas-powered counterparts, they wear down brakes, tires and the roadway slightly more, producing more teeny-tiny particles that blow into the air and can cause respiratory problems. According to the researchers, in Scotland and the Netherlands, this increase overwhelms other local-pollution benefits of removing the vehicle’s exhaust fumes. “Non-exhaust sources account for 90% of PM10 (less than 10 microns in diameter) and 85% of PM2.5 from traffic” the report says.
If true, replacing internal-combustion vehicles with electric ones might not provide the improvement in urban environments that had been hoped. Instead of breathing particulate matter from unburned fuel, people would breath tiny bits of debris.