Does intense swimming in chlorinated swimming pools leads to airway inflammatory and structural changes in elite athletes?

Published Online: December 26, 2011

Observational studies have suggested that regular chlorinated swimming pool attendance during childhood could be a risk factor for the development of asthma. Elite competitive swimmers, training many hours per day, most days of the week, in chlorinated pools show a high prevalence of airway hyperresponsiveness (AHR) and exercise-induced bronchoconstriction (EIB). Most often, these airway disorders are associated with minimal or no reported respiratory symptoms. Whether swimmers develop classical asthma due to their intense regular swimming training or represent a specific asthma phenotype remains thus to be documented.

In an original article in The Journal of Allergy and Clinical Immunology (JACI), Bougault et al performed bronchial biopsies in 23 competing swimmers aged 17 years and older. They characterized the airway morphologic changes and compared these last with those of 10 age-matched nonathletic mild asthmatic and 10 age-matched healthy subjects (no AHR, no allergy). Among the 23 swimmers of the study, 3 had a previous physician-diagnosed asthma, but none of them currently used inhaled corticosteroids or bronchodilators. Fifty-two percent of swimmers had AHR, 43% had EIB and 82% were atopic. Inflammatory and remodeling changes were observed on bronchial biopsies of competing swimmers, similar to non-athletes with mild asthma. Interestingly, the secreted mucin was increased in swimmers compared with asthmatic and healthy subjects.

The authors hypothesized a combined role of strenuous training (mechanical effect on airway remodeling?) and chlorine by-products inhalation in the development of such features in elite swimmers. However, they indicate that the physiological and clinical consequences of these changes remain uncertain and that these findings cannot be extrapolated to recreational swimmers and children attending indoor chlorinated swimming pools. They finally advised to pay particular attention to the respiratory health of swimmers, even when they do not report troublesome respiratory symptoms, and suggested that preventative measures to reduce the formation of chlorine by-products release should be considered to minimize the impact of these on the airways.


The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

AAAAI - American Academy of Allergy Asthma & Immunology