Chongqing seems incredible on pictures and YouTube videos. No doubt it's a comfortable place to live for many people, and surely it isn't perfect, especially when it comes to things like air pollution.
What amazes me is China's capacity to do development on a large scale, something that's completely missing in Europe. If we had efficient large-scale construction solved, we could really put a dent in the cost of living crisis, and reverse the overcrowding of the existing urban centers.
Lots of low-quality construction work though. Anecdotally, I used to live in a 30-story building in one of the special economic zones. My building had horrendously large cracks in the concrete, and even though I knew rationally that it wouldn't come down, it didn't feel safe, especially during typhoons, etc.
And the study calculates it a 5mg for rats as 25mg for humans.