Environmental monitoring of Disinfection by-products (DBPs) in water and air in indoor swimming pools

To evaluate the presence of volatile (THMs) and nonvolatile [chlorite, chlorate, bromate, haloacetic acids (HAAs)] disinfection by-products (DBPs) in indoor swimming pools.Some indoor swimming pools in Emilia Romagna region (Northern Italy) were visited and water and environmental air samples were collected. Sodium hypochlorite or dichloroisocyanurate were involved in water disinfection treatments. THMs in water and air were evaluated by head-space gas chromatographic technique, whereas HAAs, bromate, chlorite, chlorate in water were detected by ion chromatography with mass spectrophotometry.THMs were always present in pool water (range: 27-98 μg/L) and in environmental air (range: 39-119 μg/m3), with chloroform as the main by-product. Levels in air were persistent and higher above and around the pool than in the surroundings. Bromate was never found while among HAAs monochloro, dichloro, and trichloroacetic acids were measured in all water samples (range: 109-387 μg/L). Chlorite in pool water was rarely evidenced, whereas it was always present in water supplying the pool. Chlorate was present in source water and also in pool water samples showing unexpectedly high concentrations (range: 192- 12,537 μg/L), with an increase of about 50 times with respect to source water.THMs, as index of the total amount of volatile DBPs, represent an additional source of human exposure as present in water and air. Among nonvolatile DBPs, only HAAs and chlorate were detected, sometimes at very high levels. Chlorate, usually considered as a by-product when drinking water treatment is made by chlorine dioxide, seems associated with disinfection processes usually adopted for swimming pool water, such as sodium hypochlorite or dichloroisocyanurate. The origin and chemical reactions of nonvolatile DBPs deserve further evaluation to refine exposure for subjects attending indoor swimming pools.