COPD is a lung disease that makes it progressively harder for sufferers to breathe. It is also known as chronic bronchitis or emphysema. People who suffer from COPD have partially blocked airways- tubes carrying air in and out of their lungs. Severe COPD that causes shortness of breath and other symptoms can prevent sufferers from performing the most basic of daily functions, like walking, housework, or even dressing themselves.COPD symptoms do not normally become evident until lung damage has already occurred, and usually get worse with the passage of time. COPD sufferers occasionally have episodes where their symptoms dramatically worse. These episodes are known as exacerbations.Exacerbation symptoms include: coughing up an unusual amount of mucus, experiecing more shortness of breath than usual, color change in mucus that is coughed up. These exacerbation attacks are usually brought on by infections like pneumonia and acute bronchitis.The type of COPD that one suffers from is defined in terms of four stages: Mild COPD (stage 1), Moderate COPD (stage 2), Severe COPD (stage 3), Very severe (stage 4).Stage 1 SymptomsStage 1 usually involves a chronic cough that will not go away. Normally, mucus is brought up from the lungs during a Stage 1 episode. Lung function in this stage is defined as 80% of normal and higher.Stage 2 SymptomsSymptoms of Stage 2 COPD normally involves a chronic cough that produces large amounts of mucus, shortness of breath, and a periodic flare-up of symptoms. Lung function in Stage 2 is defined as ranging between 50-79% of normal function.Stage 3 SymptomsStage 3 is characterized by chronic cough producing much mucus, fatigue and a lowered ability to exercise, shortness of breath, repeated episodes of severe flare-ups, and a lung function between 30-49 percent.Stage 4 SymptomsStage 4 symptoms are: chronic cough producing much mucus, weight loss, severe shortness of breath, buildup of fluid in the legs and feet, bluish skin coloration, life-threatening flare-ups.Lung function in Stage 4 is defined as being less than 30%, or under 50% when associated with chronic respiratory failure. This is caused by carbon dioxide lingering in the lungs too long.