Workers in foundries, sandstone grinding, tunneling, sandblasting, concrete breaking, granite carving, and china manufacturing also encounter silica. Large silica particles are stopped in the upper airways. But the tiniest specks of silica can be carried down to the alveoli where they lead to pulmonary fibrosis. Silicosis can be either mild or severe, in direct proportion to the percentage and concentration of silica in the air and the duration of exposure. Silicosis can be prevented by measures specifically designed for each industry and each job.
Dust control is essential.
Sometimes this is accomplished by the wetting down of mines, improved ventilation, or the wearing of masks. Although a number of separate diseases can initiate pulmonary fibrosis, many times the cause is unknown. In idiopathic pulmonary fibrosis, careful examination of the patient s environmentaI and occupational history gives no clues to the cause. Some physicians and scientists believe that the disease is an infectious or allergic condition, however bacteria and other microorganisms are not routinely found in the lungs of such patients. On the other hand, the condition does sometimes appear to follow a viral-like illness.