Do you really need an independent peer-reviewed study to know if inhaling brake dust is bad for you or not?
At some point, it's important to trust your instincts. I don't think you need a medical degree to understand that inhaling tiny particles made of nasty stuff leads to bad health outcomes.
Instincts often cheat you. I'm not saying that it's healthy but Does it really have any effect at all? What's the concentration of particles? How harful is it comparing to cooking or peeling onions? Do we need to care about it at all?
At some point, it's important to trust your instincts. I don't think you need a medical degree to understand that inhaling tiny particles made of nasty stuff leads to bad health outcomes.