According to the relevant provisions of the state, it belongs to a special type of work. If you engage in this kind of work for a long time, it will be harmful to people's health and will make practitioners suffer from occupational diseases such as pneumoconiosis and silicosis. The basic physical requirement of this type of work is that the practitioner should not have a history of respiratory tract or be allergic to dust. Before taking up their posts, employees need to be trained in professional skills (such as the use of mechanical polishing equipment) and labor protection. Some places require a work permit, and some enterprises generally do not need a certificate).