For example, I've had numerous conversations where people will point to safety rating in vehicles to defend their purchasing decisions. Its simple to understand really, I want the safest car for my family/child etc, that is why I refuse to buy an older, used vehicle or prefer a sedan over SUV. Safety becomes cover for preference and defending trends like expanding pickup truck sizes since the 2000s while there is no safety rating or even objective measure of the efficacy of these self-driving systems.

Hopefully I haven't wasted your time, its just a psychological trend that I think exists.

I have training and a great deal of experience with vehicle emissions systems, but not medical training beyond first aid and CPR. I think that mostly the respiration problems are caused by particulates volatile organic compounds, oxides of nitrogen, and sulfur dioxide(which is quite nasty), mostly from diesel emissions. The catalytic converters and emission controls prevent nearly all VoC and like %90 of NOx, so the effect from passenger vehicles seems pretty small there. They do nothing to eliminate SO2, which is why we mandate DEF (diesel emissions fluid) on some diesels.

Brake dust and tire wear is another smaller contributor, though