Swimming pools: Exposure time and asthma symptoms in children

Introduction Swimming pool exposure has been suggested to cause asthma and other health effects in children by exposure to trichloramines. Aim To study the prevalence of asthma symptoms and time spent in indoor swimming pools among children. Methods A nested case-control study of 337 children with asthma and 663 controls aged 16-17 years within a longitudinal pediatric cohort from The Obstructive Lung Disease in Northern Sweden studies (OLIN). Prevalence of symptoms and exposure time at different ages were obtained by a phone interview. Skin prick testing for inhalant allergens was available from a previous examination of the cohort. Results The participation rate was high both in the original cohort (96%) and in the case-control study (80%) and the participants in the case-control study were representative. Children with asthma reported significantly more irritative eye symptoms, 22%, compared to controls (9.0%) and 5.5% of the children with asthma reported worsened asthma symptoms at indoor pools, while 1.5% had stopped attending indoor swimming pools because of asthma. All children with worsened asthma symptoms in indoor swimming pools were sensitized to at least one inhalant allergen. There was no consistent difference in the time spent in indoor swimming pools between cases and controls. Conclusion All children with worsened asthma symptoms in indoor swimming pools were sensitized to at least one inhalant allergen. There was no consistent difference in the time spent in indoor swimming pools between cases and controls.