I imagine that your immune system is somewhat weakened in a more polluted environment given your body has to mount an immune response in response to breathing in pollutants that it may make it easier for the virus to make you iller than someone else. I
don't know if it would be responsible for the spreading as more the severity of illness when you catch it
I would say their densely populated areas may be more to blame for the spreading rate.
This is just my guess
That's what i was thinking.
The term "densely populated" may have to be unpacked a bit cuz i heard that there were a lot of in-family infections. As i understand
traditional Chinese culture, households tend to be multigenerational. Is that still the case?
If it's killing mostly infants and old people (which im not saying it is), you could have several people in those categories in every household. Plus, whatever lung issues
everybody got from breathing in that air everyday.
Not good.
Edit: and i didn't even consider the quarantines, school shutdowns, and work stoppages. That means that all these highly susceptible people are all sitting in the house together all day, with your nominally "healthy and young" people, breathing the same air.