My research focuses on understanding the complex relationship between pollution and health in China. I apply cutting-edge econometric and statistical models to large Chinese population data and quantify the health impacts of air pollution. In a series papers published in leading academic journals, we show that China’s air pollution affects Chinese people’s health in both the short and long run. In the short run, higher levels of air pollution cause the elderly to die from cardiorespiratory diseases; and in the long run, air pollution significantly decreases the life expectancies of all age-groups. Compared with previous studies that focus mostly on developed countries, these findings are more relevant to the 4.5 billion people who are currently exposed to high levels of air pollution in the developing countries. They suggest that improving air quality in China will bring about significant public health benefits. I also conduct research on the consequences of environmental regulations and estimate the cost and effectiveness of various environmental regulations. I show that some regulations can be costly and the optimal environmental regulation should balance the benefit and cost.