INVESTIGATION SILICOSIS PREVALENCE IN WORKERS WHO HAD PREVIOUSLY BEEN IN AREAS OF DUST EXPOSURE

This paper investigates silicosis prevalence in workers whohave departed from work areas of dust exposure in eight differenttypes of plants, mines. The results of this investigation indicatethat patients identified with silicosis after they have departedfrom dust environments have rates of disease progress, complica-tions with tuberculosis and mortality lower than that of thetotal number of patients identified among workers exposed to dustduring the same period, and their ages of silicosis prevalenceare older. The silicosis of patients identified after departure fromareas of dust still possessed general properties of silicosis. Thatis, the rates of silicosis prevalence and progress and the rate ofmortality are closely related to the total period of exposure todust, type of work and the content of free silica in the dust towhich they were exposed. The factors that affect silicosis preva-lence among workers who have departed from these dust areasare various,but exposure to dust of high concentration and witha high content of free silica before their departure are themost important factors that leads to their developing silicosis.Because the rate of silicosis identified after workers have de-parted from areas of dust has increased from 2.35% in the 1950sto 63.04% in the 1980s, it is particularly important in futuresilicosis、control to strengthen the control and monitoring ofwho have left dust work environments, especially those olderworkers who experienced a period of exposure to dust of high con-centration and high free silica content.