The background and significance of the research

The atmospheric particle refers to the particle with extremely small grain sizes, which is one of the most important factors affecting the climate and human environment. Industrial production and human activities are the main reasons for the increase in the concentration of atmospheric particles due to pollution of the atmospheric environment. The use of China’s coal exceeds 70% of the energy consumption. As the main energy source in China, air pollution and chimney dust particle pollution caused by its combustion are extremely serious. The continuous growth of atmospheric particles seriously affects human health. Usually, particles greater than 10um can be excreted by the human body, and particles greater than 5um will be blocked by our mouth and nose and will not enter your body. Harmful substances such as bacteria, viruses, and heavy metals together with particles smaller than 2.5um will be in the circulatory system of the human body. Particulate with a size smaller than 1um will participate in the pulmonary circulation and adhere to the lung cells. If the pores of the particles adhere to carcinogens such as sulfur dioxide, nitrogen dioxide, and phenylpyrene, human health will be seriously affected. On March 5, 2016, at the fourth session of the 12th National People’s Congress, Premier Keqiang Li proposed to strengthen environmental governance, control air pollution, severely control atmospheric haze, and determine to walk along the path of economic development and environmental improvement. Therefore, the detection of fine particle PM2.5 and the application of dust sensors in real life through reliable, stable and economical solutions are of great significance in the fields of protecting human health and improving the quality of the air.

The composition of the atmospheric particle is very complex. It is a multiphase system composed of solids or liquids and gases suspended in the air. Invisible substances such as molecules, atoms, and ions are also included. The particle diameter span of natural particles is usually divided into seven grades, as shown in Figure 1.
 

Figure 1 The distribution of different particle sizes
 
It can be seen from Figure 1 that the commonly known aerosol haze (liquid particles with cohesion and dispersion) has a particle size span of 10-5 to 10-8m. The primary aerosol particles generated in natural ecosystems, such as natural fire combustion, sandstorms, volcanic eruptions, and biological particles emissions, and the secondary aerosols generated by natural gas emissions such as SO2, NO2, HS, NH3 and other gases are usually called natural aerosols; primary aerosols produced by human activities such as coal burning, industrial production and secondary aerosols converted from gases produced by human activities are called man-made aerosols. The sources of particles are diverse and the formation system is complex, and the health problems caused by harmful substances getting into the human body are becoming more and more serious.
 
With the development of science and technology and the maturity of production technology, technology related to particle concentration has been widely developed and applied. The road of win-win development of the economy and environment is also a long-term principle. Real-time measurement of environmental quality is important for protecting the environment and improving people’s awareness for environmental protection and ensuring human health. At the same time, by analyzing the relationship between the particle size span and the concentration of particles formed by the combustion of combustibles, the use of advanced dust concentration sensors also shows a good development in fire warning. The particle concentration detection scheme and the dust concentration sensor are of great significance in fire warning and indoor environmental quality detection for environmental protection, protection of people’s lives, properties and human health, and guidance of human activities.