n.
Common pneumoconiosis caused by long-term inhalation of silica mineral dust.
Known since the 18th century, it usually occurs after 1020 years of exposure in jobs such as mining, stonecutting, grinding, or polishing. The smallest particles do the most damage, killing macrophages (see reticuloendothelial system ) that engulf them in the pulmonary alveoli. Dead cells accumulate, forming fibrous masses that reduce lung elasticity. Decreased lung volume and poor gas exchange lead to shortness of breath and then to coughing, difficulty in breathing, and weakness. Patients are vulnerable to tuberculosis , emphysema , and pneumonia . In the absence of effective treatment, control of silicosis depends on prevention with face masks, proper ventilation, and X-ray monitoring of workers' lungs.