Common cold with cough on the day of examination: a factor that should be taken into account in epidemiological studies on pulmonary function.

Epidemiologists using pulmonary function tests agree that a number of factors have to be taken into account. In a study carried out among 912 men aged 22 to 54 we found that those having a common cold and cough on the day of examination had lower pulmonary function values. So we suggest that these symptoms should also be considered as a potential confounding factor.