When your airways become clogged with mucus or foreign particles such as smoke or dust, a cough is a reflex reaction that attempts to clear the particles and make breathing easier. Usually, this type of coughing is relatively infrequent, but coughing will increase with exposure to irritants such as smoke.
Similarly, you may ask, how cough is caused?
Viruses and bacteria. The most common cause of a cough is a respiratory tract infection, such as a cold or flu. Respiratory tract infections are usually caused by a virus and may last from a few days to a week. Infections caused by the flu may take a little longer to clear up and may sometimes require antibiotics.
How is cough mucus formed?
Phlegm is a slightly different substance. It's a form of mucus produced by the lower airways — not by the nose and sinuses — in response to inflammation. You may not notice phlegm unless you cough it up as a symptom of bronchitis or pneumonia.
How does cough form?
If you inhale pollutants or irritants from the air, it affects the lungs and respiratory tracts, so a cough is meant to expel them quickly from the body. Dry coughs are often the result of inflammation in the lungs or respiratory pathways, which is often caused by coughing in the first place.