It’s possible one of the worst long term pollution problems is from tire wear which is not addressed by cleaner running vehicles, so there’s multiple avenues to address there but most solutions only address the fuel/exhaust, was a hacker news story earlier this year.
The contribution of tire and brake pad wear is really quite low compared to other sources of air pollution.
From Evangeliou et al. (2020), Atmospheric transport is a major pathway of microplastics to remote regions, page 3:
"Surface concentrations of tire wear particles (TWPs) range between a few ng.m−3 and 20 ng.m−3 for PM2.5 and up to 50 ng.m−3 for PM10 (Supplementary Movie 1). Brake wear particle (BWP) surface concentrations reach 50 ng.m−3 at maximum (Supplementary Movie 1). The highest concentrations were calculated for eastern USA, Europe and South-eastern Asia. All concentrations (TWPs 0.4 μg.m−3 for PM2.5, 1.8 μg.m−3 for PM10; BWPs 0.8 μg.m−3 for PM2.5, 1.4 μg.m−3 for PM10) were far below air quality limits for PM (annual mean 10 μg.m−3 for PM2.5, double for PM10) and lower than typical black carbon (BC) concentrations in remote regions."
But the type of pollution does matter. An important question is does it have a greater impact. And given the studies linking health to distance from the freeway, I think that question needs further investigation.
Road wear scales n^4 with vehicle weight [1]. If tire wear is anything similar, it makes an additional strong argument that we should be using fewer (mass transit) and lighter (bicycles) vehicles.
Why should we be using mass transit? Wouldn't a bus be heavier than a car? And n^4 with weight would mean the increase in weight would likely be much worse than the gain from the n reduction in number of cars.
Electric (both fully and hybrid) vehicles have the advantage over fuel cell, LNG/CNG and conventional ICE engines in that they can massively reduce brake pad wear/dust by regenerative braking, so only tire wear remains as an issue.
"One is social distancing, which may have cut down on the amount of general infection from contact with others.
Another is less air pollution, from fewer cars being on the roads."
I'd love to see increased incentive for cities to act hastily on reducing <pm2.5 air pollution. Talk about a covert inequality exacerbator.