1. Chronic obstructive pulmonary disease : Causes, incidence, and risk factors  (Trust Mark: Doctor-Reviewed)
Smoking is the leading cause of COPD. The more a person smokes, the more likely that person will develop severe bronchitis. Secondhand smoke may also cause chronic bronchitis. Air pollution, infection, and allergies make chronic bronchitis worse. ...• Reviewer: Benjamin Medoff, MD, Assistant Professor of Medicine, Harvard Medical School, Pulmonary and Critical Care Unit, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

2. Subcutaneous emphysema : Common Causes  (Trust Mark: Doctor-Reviewed)
This is a rare condition. When it does occur, possible causes include: Collapsed lung (pneumothorax), often occurring with a rib fracture; Facial bone fracture; Ruptured bronchial tube; Ruptured esophagus. This condition can happen due to: Blunt t...• Reviewer: John E. Duldner, Jr., MD, MS, Assistant Professor of Emergency Medicine, Director of Research, Department of Emergency Medicine, Akron General Medical Center and Northeastern Ohio Universities College of Medicine. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.