The harm of dust to human beings

Dust is the enemy of human health, so people especially hate it. Dust flies around with many bacteria, viruses \x0d\ eggs, spreading diseases. Industrial dust and fiber dust can make workers suffer from various incurable occupational diseases. Excessive dust will also cause environmental pollution and affect people's normal life and work. ................................................................................................................................. (the harm of dust) inducing human respiratory diseases \x0d\ Benefits \x0d\ If there is no dust in the atmosphere, sunlight will not be absorbed, reflected, scattered and refracted, and the sky will be white, without snow, rain and dew, glow and rainbow. Because dust is a hygroscopic particle, without its core, water vapor in the air will not condense, and it is difficult to form clouds in the sky. Without the cover of clouds, the surface will become dry and barren, and the weather will be either too hot or too cold. Without dust, many harmful rays in the universe will break into the earth's surface without hindrance, posing a fatal threat to human beings and all kinds of creatures. In addition to these benefits, dust can condense water vapor. Let them become water drops, otherwise, everything will be wet and living things can't survive. Although dust has many shortcomings, its contribution is endless. It can make the earth get solar energy gently, and it can also make enough condensation nuclei in the atmosphere to increase the chances of clouds and rain. Adjust the surface temperature to make it suitable for the survival and reproduction of life. \x0d\ Types of dust \x0d\ Dust can be roughly divided into three types according to the particle size: \x0d\ Dust \x0d\ Dust is generated by the breaking of objects and diffuses into the air \x0d\ condensed solid smoke \x0d\ condensed solid smoke is formed during the combustion, sublimation, evaporation and condensation of substances. Its particle size is generally 0. 1 μm ~ 1 μm, which is different from dust and has great cohesion. Most of them are gases formed during the melting process of metal substances. After cooling in air, it condenses into solid smoke, and the particle shape is more regular. \x0d\x0d\ smoke \ x0d \ characteristics of dust \ x0d \ from the physical characteristics of dust, dust is an irregular solid impurity, mostly in angular, gray, brown, black and other colors, with water absorption. When there is a lot of dust in the air and the relative humidity reaches a certain level, water vapor forms water droplets, so the dust is easily wetted by water and easily absorbs water. \x0d\ According to its chemical characteristics, the composition of dust is complex, and sometimes it provides acid radicals and metal ions that lead to degradation. Some dust itself is acidic or alkaline, such as sulfuric acid smog, photochemical smog, metal oxides and other particles are alkaline. In addition, the floating dust in the dust is acidic or alkaline because of its small particle size, small surface area and strong adsorption capacity. Dust often contains substances such as clay, which will absorb moisture in the air or substances composed of archives, make it undergo hydrolysis reaction and decompose viscous aluminum hydroxide. \x0d\ Its biological characteristics: Because the spores of mold are small and heavy, they will inevitably attach to dust as the air drifts around, so dust is an ideal culture medium, breeding ground and disseminator for microorganisms. Microorganisms secrete mildew spots containing enzymes and organic acids during their growth.