Smog is a large number of particles that cannot be distinguished by the human eye, it is formed by the suspension of a large amount of smoke, dust, and multiple particles. Pollution is common in cities. Smog is the result of the interaction between specific climatic conditions and human activities. A high-density population's economic and social activities will inevitably emit a large amount of small particulate matter (PM 2.5). Once the emission exceeds the atmospheric circulation capacity and carrying capacity, the concentration of delicate particulate matter will accumulate and cause smog.