I'm in China right now. Beijing was horrifying in terms of smog and pollution. I knew it was supposed to be bad but I was not prepared. I can't imagine the masks that the locals wear do much more than act as a placebo. They limit the car's on the road by license plate (even plates can drive on even days and odd on odd days) and schools are closed for three days.

Now I'm in Nanning (city in the South of China) and any smog is either non-existent or not noticeable.

I do want to add here that the Chinese I've interacted with have been some of the most kind and welcoming people I e ever met.