1. Industrial pollution: There are some industrial enterprises around Wuyishan, and the waste gas and wastewater discharged by these enterprises will pollute the environment.

2. Traffic pollution: With the acceleration of urbanization and population growth, the number of cars is increasing. Motor vehicle exhaust contains a lot of fine particles such as PM2.5 and harmful substances such as NOX, which will have an impact on air quality.

3. Natural conditions: Wuyishan has complex terrain, low vegetation coverage and high humidity, which is also one of the reasons for poor air quality.