The nose filters, warms, and humidifies the air we breathe before sending it to the lungs. Because cigarette smoke is inhaled through the mouth, the smoke travels directly to the lungs unfiltered. Small particles of ash, tar, and tobacco are transported into the lungs where they accumulate on the walls of the windpipe, bronchi, and bronchioles.
Experts do not agree about whether or not smoking causes chronic nasal inflammation (swelling, mucus production), but most agree that for people with nasal problems, smoking makes it worse. The problems with chronic inflammation of the nose could also be linked to the negative effects of smoking on the immune system.
Napier, K. (1996). Cigarettes: What the warning label doesn't tell you. New York: American Council on Science and Health