Which pulmonary disease results from inhalation of free silica dust?

• A. Spondylosis
• B. Spondylolisthesis
• C. Silicosis
• D. Sternum

Answer: (C)

Inhalation of crystalline silica dust leads to silicosis, a lung fibrotic disease (pneumoconiosis) caused by occupational exposure to silica in activities like mining, sandblasting, or quarry work. Silica particles are inhaled and taken up by macrophages, which become activated and release inflammatory mediators that drive fibroblast activity and collagen deposition. This results in fibrotic nodules, often in the upper lung zones, and can progress to significant impairment of lung function and increased risk of tuberculosis.

The other options describe conditions not caused by inhaling silica. Spondylosis and spondylolisthesis are degenerative or mechanical problems of the spine, not the lungs. The sternum is a bone, not a disease process.