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What is Minimum duration of developing coal minor pneumoconiasis is – and explain in detail?
Coal worker pneumoconiosis (Antracosis) 

There are two general phases in coal miners pneumoconiosis


The first phase : Simple pneumoconiosis : This is associates with only little ventilatory impairment but requires 12 years of work exposure for its development.
The second phase : Progressive massive fibrosis : This is associated with severe respiratory disability and takes much longer.