Indoor swimming pools, water chlorination and respiratory health.

Swimming is generally considered to be a healthy leisure activity for both the young and old. Swimming is even often advised as the most appropriate sport for asthmatic children [1–3], mainly (but probably not solely) on the grounds that inhaling moist air is less conducive to triggering exercise-induced asthma [4]. However, for obvious reasons of microbiological safety, the water of public and private swimming pools must be disinfected [5]. The most common procedure for water disinfection consists of chlorination. As with all human and technological intervention, the use of chlorine-based products to disinfect swimming water may lead to a number of unwanted effects, in particular the presence of chlorine-containing compounds in the air. Consequently, chlorination may affect the respiratory health of either those who work as swimming attendants or instructors, or those who use the pools as customers, particularly children and the general public, but also competitive swimmers. Although the issue of the chlorination of public water supplies has received considerable attention, mainly with regard to the presence of potentially carcinogenic or teratogenic chlorinated by-products [6, 7], the respiratory hazards of chlorinated swimming water have been less well addressed. Thus, old [8, 9] and even more recent [10] reports on indoor pollution do not deal with the air of chlorinated swimming pools, despite the generally obvious and readily noticeable irritant character of this type of environment, even in well-maintained pools [11].