题目：Local air pollution and stock returns
The natural environment has a close relationship with people’s behaviour, and thus can have significant impacts on the economic output by influencing people’s decisions. This study estimates the effects of daily local air pollution on firm’s stock returns by using straw burning as exogenous shock to local air quality in harvest seasons in China. The results show that when straw burning increases the ambient air pollution levels in local areas to a large extent after three lagged days, the stock returns decrease significantly. We also find that the impact of air pollution on stock returns might be caused by the changes in investor mood. Our study offers an important counter-example for the hypothesis of efficient markets and reveals an important link between controlling air pollution and growth of capital markets.