SAPALDIA - METHODS AND PARTICIPATION IN THE CROSS-SECTIONAL PART OF THE SWISS STUDY ON AIR-POLLUTION AND LUNG-DISEASES IN ADULTS

SAPALDIA - the Swiss Study on Air Pollution and Lung Diseases in Adult s-focuses on the long term health effects of low to moderate levels of air pollutants as typically seen in different parts of Switzerland. T he aim of the SAPALDIA cross-sectional study carried out in 1997 was t o determine the prevalence of bronchial asthma, chronic bronchitis and allergic conditions in the adult population of Switzerland and to ide ntify and to determine the respective importance of potentially influe ncing factors. These could be both personal (smoking habits, allergy s tatus, family history occupation) and environmental (outdoor and indoo r pollution, aeroallergens, climate). A further aim of the cross-secti onal study consisted in the identification of individuals susceptible to present symptoms during a two year observation period and to be inc luded in the SAPALDIA follow-up study. This technical report represent s the methodological documentation for the cross-sectional study of SA PALDIA. The instruments and the methods of standardisation are present ed and discussed. The medical examination consisted of a computerised interview using a standardised questionnaire, the taking of a blood sa mple for serological tests, allergy skin testing the measurement of en dexpiratory CO and body height, and pulmonary function testing followe d by methacholine challenge testing or bronchodilatation testing. The pattern of participation and the 9651 participants of the study repres enting 59.3 % of the sample, are described. Based on information on no n-participants gained by telephone interviews and mailed short questio naires, possible selection biases are quantified and discussed.