Respiratory symptom prevalence in adults: the comparative importance of smoking and family factors.

In a study of the prevalence of chronic cough and phlegm production in a group of nearly 4000 young adults, those adults who had several children had a higher prevalvalence of these symptoms than those with few children, especially if the children suffered from bronchitis or pneumonia. Nevertheless, cigarette smoking was the factor most strongly associated with chronic cough and phlegm production in young adults in this study.