Minimum duration of developing coal minor pneumoconiasis is –: (A) 2–4 years, (B) 4–6 years, (C) 8–10 years, (D) More than 10 years
Answer is D. 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.