There are a couple dozen other elements that are in there in trace amounts, but to a first approximation you're just a bag of carbon, oxygen, and hydrogen. Now, it turns out that the atmosphere is a bag of carbon, oxygen, and hydrogen as well, and it's not living.
Cigarette smoking is the most common irritant that causes emphysema. Pipe, cigar, and other types of tobacco smoking can also cause emphysema, especially if the smoke is inhaled. Fumes and Dust. Breathing in other fumes and dusts over a long period of time may also cause the disease.
Spontaneous subcutaneous emphysema is thought to result from increased pressures in the lung that cause alveoli to rupture. In spontaneous subcutaneous emphysema, air travels from the ruptured alveoli into the interstitium and along the blood vessels of the lung, into the mediastinum and from there into the tissues of the neck or head.