Emphysema is a chronic disease affecting the lungs and respiratory tract. It is commonly caused by toxic chemicals, especially tobacco smoke. It is a progressive disease which gets worse over time. It results in shortness of breath and the inability to exert one's self in physical activity. Emphysema is caused by damage to small air sacs and airways in your lungs. This obstructs airflow when one attempts to exhale. There is no way to reverse damage done by emphysema, treatment focuses on minimizing symptoms.