There's more than just CO2 coming from combustion engines though, like nitrogen and sulfur containing compounds, which can in turn cause secondary pollution. Cumulatively, I think those pollutants have a bigger effect on human health than the road particles. Also, these road particles still get ripped up by regular cars, even if it's to a lesser extent. So overall I'm still convinced that EVs are a step in the right direction. We can't know for sure until more studies are performed.