What do you know about smog?

Smog, as the name suggests, is fog and haze. Fog is an aerosol system composed of a large number of tiny water droplets or ice crystals suspended in the air near the ground. It is the product of the condensation (or sublimation) of water vapor in the air near the ground. Haze, also known as haze (smog), particles such as dust, sulfuric acid, nitric acid, and organic hydrocarbons in the air can also make the atmosphere turbid. Smog is a state of atmospheric pollution. Smog is a general expression for the excessive content of various suspended particulate matter in the atmosphere, especially PM2.5, which is considered to be the "culprit" of causing smog. The haze warning signal is divided into three levels, represented by yellow, orange and red respectively, corresponding to the forecast level terms of moderate haze, severe haze and severe haze.

Haze is a combination of fog and haze. Smog is common in cities. In many areas of China, fog is combined with haze as a disastrous weather phenomenon for early warning and forecasting, collectively referred to as "haze weather". Smog is the result of the interaction between specific climate conditions and human activities. Economic and social activities with high density of population will inevitably emit large amounts of fine particulate matter (PM2.5). Once the emissions exceed the atmospheric circulation capacity and carrying capacity, the concentration of fine particulate matter will continue to accumulate. At this time, if affected by calm weather, etc., it is easy to occur. Widespread smog.