October 2011, VOLUME128 /ISSUE Supplement 3

Infant Swimming in Chlorinated Pools and the Risks of Bronchiolitis, Asthma and Allergy

C Voisin, A Sardella, Marcucci, A Bernard. Eur Respir J. 2010;36(1):4147
  1. Patchanee Benjasupattananun, MD,
  2. Wanda Phipatanakul, MD, MS
  1. Boston, MA


Recent studies postulated that chlorine used to disinfect swimming pools can cause airway changes and make the lungs more sensitive to infection and asthma. This study evaluated the associations between infant swimming and bronchiolitis and its sequelae among young school-aged children.


A total of 430 children aged 5 to 6 years in 30 kindergartens located mainly in the area of Brussels and Liege (Belgium) who were participating in a prospective study on the respiratory impact of air pollution were included.


Parents completed a questionnaire regarding the child's health history, respiratory symptoms (asthma, bronchitis, bronchiolitis, and pneumonia), and swimming practices (type of pools, type of disinfection method used, frequency of attendance, age started).


Attendance at indoor or outdoor chlorinated pools ever before the age of 2 years was associated with an increase risk of bronchiolitis (odds ratio: 1.68 [95% confidence interval (CI): 1.08–2.68]; P = .03). Associations persisted, and were even strengthened, by the exclusion of other risk factors. Among children with no parental antecedents of atopic diseases or no day-care attendance, odds ratios for bronchiolitis were 4.45 (95% CI: 1.82–10.9; P = .001) and 4.44 (95% CI: 1.88–10.5; P = .007), respectively, after >20 hours spent in pools during infancy. Infant swimmers who developed bronchiolitis also showed higher risks of asthma and respiratory allergies later in childhood.


Swimming-pool attendance during infancy is associated with a dose-dependent increase in risk of bronchiolitis and interacts with bronchiolitis to increase the risk of respiratory allergies later in childhood.


Recent findings raised the question of safety of infant swimming. One theory regards the possibility that compounds from the pool reduce lung Clara cell protein (CC16), which protects from inflammation in acute respiratory syncytial virus infection. To date, cross-sectional studies have found inconsistent results in association with swimming-pool attendance and respiratory diseases. However, epidemiologic studies that use data from self-limited questionnaires can be prone to recall bias. Swimming pools have a variety of chlorine compounds in the water and microaerosols, as well as other pollutants such as nitrogenous substances from bathers. These are points to clarify in these studies. Prospective longitudinal studies are needed to characterize and confirm an association between chlorinated pools and outcome in allergic and respiratory diseases.