Data collection was effected by way of an
interviewer-administered structured questionnaire, to
The heights (cm) of the subjects were measured
without shoes. Weight (kg) was measured with
minimum clothing using a bathroom scale. Lung
function tests were carried out with a vitalograph
spirometer (Vitalograph Ltd, Buckingham, UK) and
a Wright peak flow meter (Airmed, UK). The
procedures were carefully explained and
demonstrated to each subject and then the tests were
carried out. Each anthropometric or lung function
parameter was measured by a trained technician
familiar with the procedure. The use of one observer
per measurement was maintained throughout the
study. The leader of the team randomly repeated
some of the measurements to validate their accuracy.