Baseline characteristics of the study population (subset of ECRHS II).

1 Never had asthma and no lower respiratory symptoms (wheezing/whistling, tightness in chest, attack of shortness of breath during rest/activity, woken up by an attack of shortness of breath, asthma attack, medication), trouble with breathing, hay fever, runny or blocked nose without a cold, or medicine for breathing (last 12 months)2 exposure to second-hand smoke, smoke at home or during workBaseline characteristics of the study population (subset of ECRHS II).