The study looked at how environmental pollution and economic growth are related in different regions of China. They found that the amount of waste water produced increases with economic growth, but only up to a certain point. After that point, waste water decreases as income continues to rise. This suggests that waste water treatment in China is well-developed. On the other hand, the amount of exhaust gas produced also increases with economic growth, but again, only up to a certain income level. This shows that China still needs to improve its treatment of exhaust gas to better protect the environment.