What causes the smog in Yantai?

There are several reasons for the smog weather.

1. The main factor when the atmospheric pressure is low and the air does not flow. 2. The ground is dusty and the air humidity is low. People and vehicles on the ground stir up dust. 3. Automobile exhaust is a factor of smog. 4. Secondary pollution produced by factories. 5. CO2 and other pollutants emitted by heating in winter.