What are the air pollutants?

Air pollution pollutants include: soot, total suspended particles, respirable suspended particles (floating dust), nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone and volatile organic compounds.

Air pollutants are a mixture of gaseous substances, volatile substances, semi-volatile substances and particulate matter (PM), and their composition changes very obviously. The composition of air pollution is influenced by many factors, including meteorological conditions, different times of the day, different days of the week, industrial activities and traffic density.

Due to different sources, the chemical composition of particulate matter in the air is obviously different. For example, the earth's crust particles (soil and beaches) are mainly silicon dioxide, but in industrial activities and transportation, the particles produced by burning fossil fuels contain a lot of carbon: various components in air pollution constantly interact with each other, and they also interact with the atmosphere.

Source of pollutants:

The formation and emission of many different pollutants and chemicals come from natural processes in the earth's crust, such as particulate matter emitted by volcanic eruptions and gas pollutants such as sulfur dioxide, hydrogen sulfide and methane. Forest fires can also cause air pollution, releasing smoke, soot, unburned hydrocarbons, carbon monoxide, nitrogen oxides and dust.

Particles from tsunami, bacterial spores in soil, pollen and dust are also natural "contributors" to air pollution. Plants and trees are also sources of hydrocarbons. The blue haze over the mountain forest area is mainly the atmospheric reaction of volatile organic compounds produced by plants.

Man-made sources are the main aspects of air pollution, which mainly come from people's production activities and daily activities (industry, transportation, various combustion and garbage disposal, etc.). ). Man-made sources can be divided into special sources and comprehensive sources. If people can clearly point out that the pollutants contained in the air come from a certain emission source, the source is called a special source.

Special source usually refers to the only emission of some air pollutants from individual large factories. If there are multiple emission sources in an area, fixed or moving, it is impossible for people to judge that they come from a specific source according to the composition and properties of pollutants contained in the air. Such sources are collectively referred to as integrated sources.