The exact causes is still not known but it is believed to be caused by inhalation of polutant. These stuffs cause immune reaction that somehow destroy your alveoli.
And/or smoking can cause emphysema, weakening/eating away the thin skin tissue of your lungs.
There are many causes of emphysema. Examples of causes of the disease emphysema include smoking drugs such as the one known as "weed", smoking tobacco products, and air pollution.
Smoking many packs of cigarettes for many years can eventually cause emphysema.
Cigarettes smoking is the major cause of emphysema,
Smoking!
emphysema
The related link below will tell you everything about emphysema, causes and treatment.
Tar.
Emphysema causes lower oxygen levels in the blood.
Heavy cigarette smoking causes about 80-90% of all emphysema cases
Nicotine
emphysema
the toxins destroy you lungs and immune system.
emphysema
The answer is: Tar
emphysema
emphysema