What are the primary causes of bronchitis?

What are the primary causes of bronchitis?

Richard Sheldon (Medical Advisor to the CA State Respiratory Care Board) gives expert video advice on: How is bronchitis usually treated?; Should I take antibiotics for bronchitis?; What is the difference between bronchitis and pneumonia? and more...

The primary cause of bronchitis is smoking. I'll do everything I can to attack the habit of smoking. Of course, viruses are in there, too, and bacteria and fungi, noxious compounds. But when you realize that there are people who will take a pack of cigarettes, 20 cigarettes--8 puffs per cigarette, 20 times a day--and blow down into their lungs some very, very noxious material, you can understand how the airways will become inflamed after a while, and especially after years and years of this. So probably the leading issue with us pulmonologists and bronchitis is, of course, smoking. But then there are the things that we can't control, such as viruses, which cause a significant problem.