RELATION OF EXPOSURE TO AIRWAY IRRITANTS IN INFANCY TO PREVALENCE OF BRONCHIAL HYPERRESPONSIVENESS IN SCHOOLCHILDREN

To find out whether exposure to sulphur dioxide during infancy is related to the prevalence of bronchial hyperresponsiveness (BHR), we studied schoolchildren (aged 7-13 years) from two areas of Norway-a Valley containing a sulphur-dioxide-emitting aluminium smelter and a similar but non-industrialised valley. Bronchial responsiveness was assessed in 529 of the 620 participants. The median exposures to sulphur dioxide and fluoride were 37.1 mu g/m(3) and 4.4 mu g/m(3) at ages 0-12 months and 37.9 mu g/m(3) and 4.4 mu g/m(3) at 13-36 months. The risk of BHR increased with exposure to sulphur dioxide and fluoride at these ages; the odds ratio for a 10 mu g/m(3) increase in sulphur dioxide exposure at 0-12 months was 1.62 (95% CI 1.11-2.35) and that for a 1 mu g/m(3) increase in fluoride exposure was 1.35 (1.07-1.70) at 0-12 months and 1.38 (1.05-1.82) at 13-36 months. Exposure to these low concentrations of airway irritants during early childhood is associated with an increased prevalence of BHR in schoolchildren.