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.
Subcutaneous Emphysema Causes. One of the basic causes of subcutaneous crepitation is the seepage of air through the lacerations on skin caused by stabbing, blunt trauma or bullet wounds. Due to the muscular movements the air is readily drawn in and rapidly spreads to the neck and chest cavity.