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Ann Occup Hyg. 2012 Apr;56(3):264-77. doi: 10.1093/annhyg/mer125. Epub 2012 Jan 23.

Assessment of occupational and public exposure to trichloramine in Swiss indoor swimming pools: a proposal for an occupational exposure limit.

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Laboratoire intercantonal de santé au travail, 2034 Peseux, Switzerland.



The presence of trichloramine in the air in different indoor swimming pools has been studied in several countries. In almost all studies, the results show a possible health impact due to trichloramine among pool attendants. The main objectives of our study were to evaluate, for the first time in Switzerland, occupational and public trichloramine exposure in a representative panel of indoor pools and to propose an occupational exposure limit for trichloramine.


Measurements were done in 30 indoor swimming pools located in three regions of Switzerland: Jura, Neuchâtel, and Fribourg. All investigations were performed during the 2007-2008 winter season in order to assure closed windows and standard ventilation conditions. Trichloramine air samplings were performed at 130 cm above the floor around the pool. Analyses of free chlorine and bounded chlorine were performed on-site, and water samples were immediately sent to the laboratory for analysis of trihalomethanes, urea, and dissolved organic carbon. A health questionnaire was distributed to all the participants.


Our results indicate that in all the studied facilities except one, the trichloramine concentrations were below the French reference value of 0.5 mg m(-3), and only three were equal to or slightly over 0.3 mg m(-3). Overall, our results point out a very low and consistent range of trichloramine concentrations (mean concentration of trichloramine: 0.114 ± 0.043 mg m(-3)). A total of 184 questionnaires were filled out by pool workers. Of the study population, 66% were men (n = 117), 21% were smokers (9 women and 29 men), and only 7% (n = 13) were ex-smokers. The control group was composed of 71 persons (38 men and 33 women); 22% (n = 15) were smokers and 24% (n = 16) ex-smokers.


Our results demonstrate an increasing risk of irritative symptoms up to a level of 0.2-0.3 mg m(-3) of trichloramine. The health data in our study, as well as the review of the literature, strongly suggest fixing the trichloramine occupational exposure limit at 0.3 mg m(-3). Severe technical standards (on flocculation, filters, water flow, and ventilation systems) and regulations on water quality (free and combined chlorine, urea, and amount of fresh water) contribute to reducing trichloramine formation and, consequently, occupational and public trichloramine exposure. In addition, to ensure good public hygiene (showering before swimming), correct and regular public awareness campaigns should be undertaken.

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