The lungs are an organ of elimination-cleansing, like the liver and kidneys. When the liver and kidneys are over-burdened, the task falls to the lungs and skins to get rid of toxins or over-abundant minerals.

Coffee is actually considered helpful to asthmatics; and coffee is also, curiously, a source of omega-3's, like chocolate. But again like chocolate, it should be consumed moderately. It's also quite acid and can throw the body's acid-alkaline balance off.
I've read that drinking regular black tea will offset the negative contribution from caffeine in coffee because it is rich in tannin.

I just read in another cure zone post about a man's research on Colloidal Silver in nebulizer helping rid the lungs of tarry deposits. I've never heard of 'crystaline' deposits in the lungs, but it might be worth researching if it acts on that, also.