Reduced greenhouse gases is an often talked about subject with zero emission EV's but there is another type of pollution that can be easily reduced  with EV's using regenerative braking.  Regenerative braking minimizes the use of the traditional friction braking which produces the black dust particles of metal and whatever brake pad material you often see accumalated on your car, roads, signs, overpasses and even nearby flora. There is no production of black dust particles when using regenerative braking because the car is slowed down electromagnetically and not by friction.  A recent study explains why the brake dust can be harmful to our respiratory system.

 "Metals from brakes and other automotive systems are emitted into the air as fine particles, lingering over busy roadways. Now, researchers at Georgia Institute of Technology have shown how that cloud of tiny metal particles could wreak havoc on respiratory health."

 "In a study published January 31 in the journal Environmental Science & Technology, the researchers described how vehicle-emitted metals such as copper, iron and manganese interact with acidic sulfate-rich particles already in the air to produce a toxic aerosol."

“Sulfate has long been associated with adverse health impacts,” said Athanasios Nenes, a professor and Georgia Power Scholar in the School of Earth & Atmospheric Sciences and the School of Chemical & Biomolecular Engineering. “The old hypothesis was that the acidic sulfate burns your lung lining, which in turn leads the bad health effects. But there is not enough acid in the air alone to really have that impact.”

“There’s a chain reaction happening in the air above busy highways,” said Rodney Weber, a professor in Georgia Tech’s School of Earth & Atmospheric Sciences. “Acidic sulfate in the atmosphere comes into contact with those metals emitted from traffic and changes their solubility, making them more likely to cause oxidative stress when inhaled.”

“That’s the smoking gun,” Nenes said. “The sulfate essentially dissolves those metals; when you breathe in those particles, the metals could be absorbed directly into the blood stream and cause problems throughout the body. For the first time, a mechanism emerges to explain why small amounts of acidic sulfate can adversely affect health.”