Passage: A chronic cough is often the first symptom to develop. Early on it may just occur occasionally or may not result in sputum. When a cough persists for more than three months each year for at least two years, in combination with sputum production and without another explanation, it is by definition chronic bronchitis. Chronic bronchitis can occur before the restricted airflow and thus COPD fully develops. The amount of sputum produced can change over hours to days. In some cases, the cough may not be present or may only occur occasionally and may not be productive. Some people with COPD attribute the symptoms to a "smoker's cough". Sputum may be swallowed or spat out, depending often on social and cultural factors. Vigorous coughing may lead to rib fractures or a brief loss of consciousness. Those with COPD often have a history of "common colds" that last a long time.

Question: What factors determine whether sputum is swallowed or spit out?
social and cultural