Bronchial Responsiveness in Children Exposed to Atmospheric Pollution in Hong Kong: Subjects
During the period January 1989 to December 1990, maximum daily levels of one or more of the following pollutants, sulfur dioxide (S02), nitrogen dioxide (N02), total suspended particulates (TSP), respirable suspended particulates (RSP), and ozone (O3), exceeded World Health Organization recommended standards on four occasions in KDT. No excess levels were reported for SDT.
Eleven schools, five in KDT and six in SDT, were recruited to participate in the respiratory health study. The method of sampling has been described elsewhere. Altogether, 3,513 children, 2,027 from KDT and 1,486 from SDT, were enrolled in the first year of the study in 1989 and examined from April to May. The prevalence of respiratory symptoms was higher in the KDT, but no differences were found in standard lung function tests (FEVi and FVC). In the second year (1990), the respiratory health inquiries were repeated in the same months.
In addition, a subset of four schools, two in each district, was chosen to participate in the histamine challenge tests; one class from each of primary 4 and primary 5, in both morning and afternoon sessions, was randomly selected from each of the schools, with 534 children eligible for testing. Anti allergy medicine website Children with a history of either asthma medication use or wheezing on the dav of testing were not included. Because of the regionalization policy for positioning schools, more than 95 percent of the children resided in the same district in which their school was located, and there was no difference between districts in the children’s duration of residence. Written consent was obtained from the parents for their children to participate in the study, and both parents and children completed a questionnaire which included questions on the respiratory health of the children and the parents, household smoking habits, and a number of demographic variables. The parents returned the completed questionnaire to the school, and the children answered their questionnaire independently in the classroom under controlled conditions and instruction by one of the senior investigators. In this study, responses from the children’s questionnaires were used to identify those with histories of wheezing and/or diagnosed asthma; agreement with the parents questionnaires was >95 percent.