I don't smoke.and i work in a clean environment.i suffer from a mvp & difficulty in breathing.most of the days ,my mucus has black specks in it.why?

Mucus : It is possible to have black discharge in mucus if exposed to dirty environments such a poor air condition, heavy polution, around second hand smokers. This is your body trying to get rid of tar like products via ciliary clearence. These air cells that have hair like structures that move particulants out of the lung. These are the first cells to die in smokers, or people using hookah.