What are the main causes of haze weather?

Atmospheric aerosols that form haze weather come from natural emissions and human activities. In a period of time, the total amount of aerosol particles emitted by natural and human activities is basically stable. Then why sometimes there will be severe haze weather, and sometimes there will be blue sky and white clouds? The decisive control factor is meteorological conditions. In addition to the sources of atmospheric particles, low-level advection transport conditions, low-level vertical mixing conditions, atmospheric diffusion ability and atmospheric scavenging ability will all affect the generation of haze.