1. Dust is a tireless traveler on the earth, and it drifts away with the air turbulence.

2. Dust is generally hygroscopic. Water vapor must be on dust to become small water droplets, which can float in the air for a long time. Otherwise, the ground is completely wet and human beings can't survive.

3. If there is no dust, strong sunlight will make people unable to open their eyes, because dust will absorb part of the sunlight and scatter it around, just like countless electric light sources. The intensity of sunlight is greatly weakened by the scattering of dust, so it becomes soft. Dust has many uses. Without dust, the sky will always be blue and everything on the ground will be wet, which will make the natural weather disappear.

The diameter of dust particles is generally between one millionth of a millimeter and several hundredths of a millimeter. The dust that the human eye can see is a giant in the dust, and the tiny dust can only be seen under the electron microscope. The main source of dust on land is. Industrial emissions, burning smoke and dust, soil dust, etc.

The air around us is almost everywhere, from indoor to outdoor, from city to country, from plain to mountain, from desert to ocean. A truly dust-free space can only be created in the laboratory.

6. Under a clear sky, dust is invisible. Only when the sun shines into the dark room through the cracks in the shutters can you clearly see countless dust flying in the air. Of course, big dust can be seen by naked eyes, and small dust is smaller than bacteria and cannot be observed by microscope.