Why does prolonged smoking make your voice deeper?

What biological mechansims are at work that give a long-time smoker a deep, raspy voice? Inherent in this question, I suppose, is how do you get your tone in the first place? Does smoking cause some sort of thickening? Are cilia involved?

cigarette smoke provokes effects similar to those of inflammation: redness, swelling, increased mucus production, and thickening of the surface lining or mucosa. Both the smoke particles and the heat of the inhaled fumes appear to damage the mucosa. Interestingly, unfiltered marijuana smoke causes even greater irritation to the throat and trachea than does tobacco smoke.

A laryngologist can recognize smokers just by the typical appearance of their nose and throat: nicotine staining of the nasal hairs, dry throat, dry swollen vocal cords, and tenacious secretions. Singers who smoke have a harsh breathy voice and a loss of clarity in their upper range. Women who smoke may suffer from polyps on their vocal cords and severe degeneration, polyps which have the appearance of big balloon blisters. Persons with chronic smoking-related inflammation often develop leukoplakia, or white patches on the lining of the throat, a known precursor of cancer.