Spirometric reference standards for preschool children in Hong Kong.

1. Prediction equations and normograms are established using incentive spirometry in a community cohort of 770 Hong Kong Chinese children aged 2 to 6 years. 2. All spirometric parameters depend mainly on standing height. Boys have higher values than girls. 3. Forced expiratory volumes depend on birth weight, place of birth, history of wheezing, and environmental tobacco smoke (ETS) exposure. 4. High urinary cotinine level as a biomarker of ETS exposure is noted in about one tenth of the children. 5. Urinary cotinine level is inversely associated with all spirometric parameters. This supports implementation of the smoking cessation programme.