I was in L.A. in the 60s. Passing through. My eyes were watering and I didn't know why. I went into a Bank and the woman looked at me and said "It must be pretty bad out there". I said "What do you mean?". She said "Your eyes". So, that was my first experience with SMOG. Your eyes literally burn.
So, I'm no rocket scientist, but cars are belching out all kinds of unhealthful ****.
"Burning gasoline and diesel fuel creates harmful byproducts like
nitrogen dioxide, carbon monoxide, hydrocarbons, benzene, and formaldehyde. In addition, vehicles emit carbon dioxide, the most common human-caused greenhouse gas."
https://ecology.wa.gov/Issues-and-local ... -pollution