This is the medical term often used to describe shortness of breath or difficulty breathing. When you are suffering from COPD, your lungs are not functioning properly. This can cause your lungs to provide inadequate oxygen to the heart and working cells in the body and when you are low in oxygen, you may feel short of air. This is a common symptom in a variety of disease processes so if you notice that you are having troubles breathing and you have not exerted very much, this could indicate that something is not right with your body. Make sure to have your doctor assess your health if you feel any shortness of breath.