Pneumoconiosis is caused by occupational exposure to productive dust. There is a clear dependence between the occurrence of pneumoconiosis and the amount of dust exposure, i.e., the dust exposure must reach a certain amount to cause pneumoconiosis. I. Sources of productive dust in terms of their production methods, there are mainly the following: 1. Mechanical processing of solid substances, such as crushing of minerals, drilling, grinding, polishing, cutting, crushing of solid substances, sieving, mixing, transportation and so on, the processing of organic substances, textiles, etc. This is the most important source of productive dust in terms of occupational exposure. This is the most important source of productive dust. 2, incomplete combustion of solid substances or blasting, such as incomplete combustion of coal produced by the smoke containing a large amount of coal dust, mining and tunnel blasting. 3, the steam generated when the material is heated in the air condensation and hydrocarbon formation of solid particles in the form of aerosol dust, such as welding fumes generated in the welding process. Casting and metal processing in the metal fumes produced in the dust. 4, solid dusty material packaging, handling, mixing, stirring and so on. Second, the source of productive dust on its production categories, almost all walks of life do not produce productive dust, mainly in the following industries: 1, mining: a variety of metal mines and non-metallic mining 2, machinery processing industry: foundry sand, sand mixing, molding, and casting of the box, sand, etc.. Metal cutting, grinding, polishing and so on. 3.Smelting industry: metal smelting can produce a lot of metal fumes. 4.Building materials, refractory materials, glass manufacturing, cement manufacturing, quarrying, and ceramics and enamel industry. 5, road building industry: railway, highway construction in the tunnel cutting and paving. 6, water and electricity industry: water conservancy and electricity industry in the tunnel excavation and transportation.