ORIGINAL ARTICLE Airborne trichloramine (NCl 3 ) levels and self-reported health symptoms in indoor swimming pool workers: dose-response relationships Guglielmina Fantuzzi 1 , Elena Righi 1 , Guerrino Predieri 1 , Pierluigi Giacobazzi 1 , Berchotd Petra 1 and Gabriella Aggazzotti 1 The hypothesis that attendance at indoor chlorinated swimming pool is a risk factor for irritative ocular and respiratory symptoms and bronchial asthma is well known in literature, although epidemiological evidence is still inconclusive. The aim of this study was to evaluate the association between airborne trichloramine (NCl 3 ) levels and irritative symptoms in swimming pool employees in order to obtain detailed data regarding dose-response relationships and to identify the airborne NCl 3 exposure level, if any, without health effects. A total of 20 indoor swimming pools in the Emilia Romagna region of Italy were included in the study. Information about the health status of 128 employees was collected using a self-administered questionnaire. Exposure to airborne NCl 3 was evaluated in indoor swimming pools by a modified DPD/KI method. The results of the study evidenced a mean value of airborne NCl 3 of 0.65 ± 0.20 mg/m 3 (ranging from 0.20 to 1.02 mg/m 3 ). Both ocular and upper respiratory symptoms, in particular red eyes, runny nose, voice loss and cold symptoms, were declared more frequently by lifeguards and trainers when compared with employees working in other areas of the facility (office, cafe, and so on). Pool attendants exposed to airborne NCl 3 levels of 40.5 mg/m 3 experienced higher risks for runny nose (OR: 2.91; 95% CI: 1.22--6.93) red eyes (OR: 3.16; 95% CI: 1.46--6.82), voice loss (OR: 3.56; 95% CI: 1.60--7.95) and itchy eyes (OR: 2.23; 95% CI: 1.04--4.78) than other employees. Moreover, red eyes, itchy eyes, runny nose and voice loss are related to airborne NCl 3 levels, with strong dose-response relationships. In conclusion, this study shows that lifeguards and trainers experience ocular and respiratory irritative symptoms more frequently than employees not exposed. Irritative symptoms become significant starting from airborne NCl 3 levels of 40.5 mg/m 3 , confirming that the WHO-recommended value can be considered protective in occupational exposure to airborne NCl 3 in indoor swimming pools. Journal of Exposure Science and Environmental Epidemiology (2013) 23, 88--93; doi:10.1038/jes.2012.56; published online 27 June 2012 Keywords: swimming pools; trichloramine in ambient air; ocular and respiratory irritative symptoms; lifeguards and pool attendants INTRODUCTION The hypothesis that attendance at indoor chlorinated swimming pool is a risk factor for irritative ocular and respiratory symptoms and bronchial asthma is well known in literature, although epidemiological evidence is still inconclusive, especially with regard to the onset of bronchial asthma. 1 The presence of respiratory symptoms and bronchial asthma in people attending indoor swimming pools is generally linked to the environmental exposure to chloramines, N by-products of pool water chlorination treatments, and in particular to trichlor- amine (NCl 3 ), which is the most irritant and volatile compound among chloramines. 2--4 Epidemiological studies have been performed to investigate the association between human exposure to chemical derivatives of pool water chlorination and health complaints, both in swimmers, mainly in children, and in swimming pool workers. 1,2,5--13 Regarding occupational exposure, acute respiratory symptoms in swimming pool instructors were found to be associated with airborne NCl 3 levels, for the first time, by He ´ ry et al. 2 in 1995. In the study, swimming pool instructors declared to have complaints of ocular and respiratory irritation starting from an airborne NCl 3 value 40.5 mg/m 3 ; as a consequence, this value has been suggested as a ‘‘comfort’’ limit value. 2 Since then, ocular and respiratory symptoms in swimming pool employees were reported in literature, both in accidental conditions with acute exposure to chlorine derivatives and in ‘‘normal’’ working conditions in indoor swimming pools. 5,9,13--15 Studies in France, and more recently in The Netherlands and in Italy, clearly evidenced that swimming pool workers, and in particular lifeguards and trainers, are at increased risk of developing ocular and respiratory irritative symptoms. 5,9,13 The onset of bronchial asthma induced by airborne NCl 3 exposure in pool workers is a more controversial aspect. In the French study, no association between a cumulative airborne NCl 3 exposure index and occupational asthma was found. 5 Instead, occupational asthma attributed to NCl 3 exposure was reported in two lifeguards and one swimming teacher by Thickett et al. 16 in 2001, although the mechanisms of induced asthma were not completely explained. More recently, an excess risk for respiratory symptoms indicative of asthma was observed in swimming pool employees in the Netherlands. 9 In the study, asthma-related symptoms such Received 16 January 2012; accepted 1 May 2012; published online 27 June 2012 1 Department of Public Health Sciences, University of Modena and Reggio Emilia, Via G. Campi, 287, 41125 Modena, Italy. Correspondence to: Professor Guglielmina Fantuzzi, Dipartimento di Scienze di Sanita ` pubblica, Via G. Campi, 287, 41125 Modena, Italy. Tel.: þ 39 059 205 5473. Fax: þ 39 059 205 5483. E-mail: guglielmina.fantuzzi@unimore.it Journal of Exposure Science and Environmental Epidemiology (2013) 23, 88 -- 93 & 2013 Nature America, Inc. All rights reserved 1559-0631/13 www.nature.com/jes