What are the components of PM2.5?

The source of PM2.5 is complex, and the composition is naturally also very complex. The main components are carbon elements, organic carbon compounds, sulfates, nitrates, and ammonium salts. Other common components include various metal elements, including elements rich in the earth's crust such as sodium, magnesium, calcium, aluminum, and iron, as well as heavy metal elements mainly derived from human pollution such as lead, zinc, arsenic, cadmium, and copper.