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• Cause of permanent disability and mortality
• Caused by inhalation of dust containing free silica or silicon dioxide (SiO2)
• First reported in India in 1947 from Kolar Gold Mines (Mysore)
• Silica exposure occurs in industries like:
– Mining of:
• Coal
• Mica
• Gold and Silver
• Lead, Zinc, Manganese etc.
– Pottery and ceramic
– Sand blasting
– Metal grinding
– Building and construction
– Rock mining
– Iron and steel etc.
• Higher the concentration of free silica in the dust, greater the hazard
• Longer the duration of exposure, the greater the risk of developing silicosis
• Incubation period may vary from months up to 6 yr. of exposure depending upon previously discussed factors
• Particles ae ingested by phagocytes, these phagocytes block the lymph channels
• Pathology:
– Dense ‘nodular’ fibrosis
– Nodules range from 3 – 4 mm in diameter
• Clinically:
– Insidious onset
– Early manifestations include
• Irritant cough
• Dyspnea on exertion and
• Pain in the chest
– Impairment of TLC common in advanced stage
• Lab investigations:
– Xray: ‘snow – storm’ appearance
• Silicosis increases the proneness to tuberculosis
• No effective treatment as Fibrotic changes irreversible
• Prevention and control of silicosis:
– Rigorous dust control measures
– Regular physical examination of workers
– Silicosis is a notifiable disease under Factories Act 1948 and Mines Act 1952
• Chapter 1 - Dust: Definitions and Concepts; Hazard Prevention and Control in the Work Environment: Airborne Dust WHO/SDE/OEH/99.14 available at:, accessed on 16th Feb 2017
• Park’s Textbook of Preventive and Social Medicine

Types of Pneumoconiosis:






Farmer’s Lung:

Lecture on Pneumoconiosis: