What are the main sources of smog pm2.5?

Natural sources include dust in the air, volcanic ash, forest fires, floating sea salt, pollen, fungal spores and bacteria.

However, the main source of PM2.5 is man-made emissions.

Humans not only directly emit PM2.5, but also emit some gas pollutants, which are converted into PM2.5 in the air.

Direct emissions mainly come from combustion processes, such as the combustion of fossil fuels (coal, gasoline and diesel), biomass (straw and firewood) and garbage incineration.

The main gaseous pollutants converted into PM2.5 in the air are sulfur dioxide, nitrogen oxides, ammonia and volatile organic compounds.

Other anthropogenic sources include road dust, construction dust, industrial dust and kitchen smoke.

The source of M2.5 is complicated, and the composition is naturally complicated.

The main components are elemental carbon, organic carbon compounds, sulfates, nitrates and ammonium salts.

Other common components include various metal elements, such as sodium, magnesium, calcium, aluminum and iron, and heavy metal elements such as lead, zinc, arsenic, cadmium and copper, which are mainly caused by human pollution.