Or you could just make a city car-free. There are so many benefits besides fewer particles in the air. People can walk and cycle safely. Kids can play in the streets. The atmosphere is so much nicer, since people are not isolated by walls around them.
I have lived in a city with a (nearly) car-free city center (+ separate bike lines for many roads outside the center) for most of my adult life [1] and it is just glorious. Most locals just walk or cycle. Longer distances by (electric) bus or train.
I have lived in a city with a (nearly) car-free city center (+ separate bike lines for many roads outside the center) for most of my adult life [1] and it is just glorious. Most locals just walk or cycle. Longer distances by (electric) bus or train.
[1] https://en.wikipedia.org/wiki/Groningen#Cycling_and_walking