1.) Air pollution. In your typical big cities, e.g Beijing, it average AQI 100-150 for the past 10+ years https://young-0.com/airquality/. In other lower tiered cities, it average between 50-100. Just to compare, WHO recommend only AQI of 25 in 24 hour span to be ok for your health. And even though recently Beijing's AQI has gone down, what the government has done is they pushed the coal-burning factories into the countryside, and moving the pollutions there.
2.) Water pollution. Cancer causing ingredients have been found in several water sources. for example: "Shanghai water supply hit by 100-tonne wave of garbage " - https://www.theguardian.com/world/2016/dec/23/shanghai-water... https://qz.com/113751/only-3-of-shanghais-river-and-lake-wat...
3.) Smoking/smokers everywhere. "Smoking Will Kill 200 Million In China This Century" https://www.huffingtonpost.com/entry/smoking-will-kill-200-m...