Oxygen mechanism doesn't work. Any advice?

Instead the doctors say that some dust particles are present inside his lungs which has led to this problem.
Never in his life he has smoked, nor he is alcoholic. yes, but one thing he has worked in a manufacturing company.. which produces ferroalloys. I think, because of the coal dust which takes part in manufacturing process has filled up the void spaces inside the lungs.

But, It has been 3 years he is retired now. Now he gets more breathing problems whenever he steps out. I think the dust on the road has also entered into the lungs.

But sir, thank you so much for kind response. May I know your email Id and contact number so that I can contact you for which I shall remain ever grateful to you.