The local resident spoke in the video, that 10 - 20 years ago, it was quite different. (there could have been other factors effecting your visit time, such as weather, season etc, also there's 40k newcomers each year, so that would be an extra ~300k people to pollution) The problem isn't that huge. 500k houses, using coal for heating. Multiple ways to solve that, for less than ~$500M i guess.