Causes
Cigarette smoking is the number one cause of emphysema. A burning cigarette emits over 4,000 different chemicals, many of which are carcinogenic (cancer-causing) or otherwise toxic to living tissue. Although smoking has decreased in North America since 1964, it's still a major concern among young people. One-fifth of people who have smoked a pack of cigarettes a day for 20 years have obstructed airways. 5 out of every 6 lung cancer victims are smokers. A huge majority of emphysema sufferers have smoked heavily in the past.
Infections of the respiratory tract can also destroy lung tissue and thus contribute to the development or worsening of emphysema. Likewise, having emphysema increases the likelihood of infection.
Heredity is occasionally a factor in emphysema. People who are carriers of a specific genetic abnormality called homozygous 1-antitrypsin deficiency are at high risk of developing emphysema. However, it is relatively rare and accounts for less than 1% of cases. If you have 1-antitrypsin deficiency, it's vital not to smoke.
Aging naturally brings changes to the lungs and air sacs even in non-smokers. The loss of elasticity can eventually become severe enough to be classified as emphysema. Air pollution can also irritate the lungs and cause emphysema, although pollution alone is rarely the cause.