On the one hand, making strict laws is the most straightforward way to protect the environment. Environmental degradation has “externalities”, meaning that many companies ignore their environmental responsibility in order to reduce the cost of production. Because it is impractical for voluntary environmental protection to cover all the high-polluting industries, governments making strict laws and emission standards is necessary. Through punishment and production bans to increase the cost of acting illegally, which will enforce enterprises and individuals to alter their behaviours. As a result, contamination will be reduced massively and systematically.