Kotsiou OS, Peletidou S, Vavougios G, et al. - Researchers compared young swimmers with asthma attending an indoor chlorinated pool with healthy swimmers with regards to fractional exhaled nitric oxide (FeNO) levels before and after training, and to investigate the potential risk of exposure to chlorine as a factor related to bronchial inflammation. They enrolled 146 children (8-18 years old) regularly visiting an indoor chlorinated swimming pool, in whom spirometry and FeNO measurements were carried out 30 minutes following their appearance at the pool and quickly post-exercise. They asked a random subgroup of 14 swimmers, including 10 with asthma and 4 without, to undergo cardiopulmonary exercise testing, and assessed preexercise and postexercise spirometric and FeNO levels in these individuals as well. Findings revealed elevated FeNO levels prior to- and post-swimming in swimmers with asthma not observed in a different exercise field, the possible explanation for which is the presence of chlorine in the indoor swimming pool.