Emphysema is a chronic lung condition where the alveoli in your lungs are slowly damaged and destroyed.  The alveoli are small air sacs in your lungs that make breathing possible.  These tiny sacs allow oxygen and carbon dioxide to be exchanged between the lungs and the bloodstream.  When these air sacs become compromised, it makes it difficult for your body to get the oxygen it needs, and makes breathing difficult.  Emphysema is part of a group of lung diseases known as chronic obstructive pulmonary disease, or COPD.   The most common cause of this pulmonary obstructive disease is smoking.  Although it may take years to develop, emphysema is characterized by symptoms like shortness of breath, chronic cough, wheezing, fatigue, and chest tightness.