Can CO2 sensors in the ventilation system of a pool facility help reduce the variability in the trihalomethane concentration observed in indoor air?

Full-scale multisampling and empirical modeling of DBPs in water and air of indoor pools

Disinfection by-products (DBPs) are formed in the water in swimming pools due to reactions between disinfectants (chlorine, bromine, ozone) and the organic matter introduced by bathers and supply water. High concentrations of DBPs are also reported in the air of indoor swimming pools. Based on a robust multisampling program, the levels and variations of DBPs in the air (trichloramine [TCAM] and trihalomethanes [THMs]) and water (THM) were assessed, as well as their precursors (total organic carbon, water temperature, pH, free, and total chlorine) and proxies (CO2 and relative humidity) in four indoor chlorinated swimming pools. High-frequency sampling was conducted during one high-attendance day for each pool. This study focused on parameters that are easy to measure in order to develop models for predicting levels of THMs and TCAM in the air. The results showed that the number of bathers had an important impact on the levels of THMs and TCAM, with a two-to-three-fold increase in air chloroform (up to 110 μg/m3) and a two-to-four-fold increase in TCAM (up to 0.52 mg/m3) shortly after pools opened. The results of this study for the first time showed that CO2 and relative humidity can serve as proxies for monitoring variations in airborne THMs and TCAM. Our results highlight the good predictive capacity of the developed models and their potential for use in day-to-day monitoring. This could help optimize and control DBPs formation in the air of indoor swimming pools and reduce contaminant exposure for both pool employees and users.

Advances and research needs for disinfection byproducts control strategies in swimming pools

The control of disinfection byproducts (DBPs) in swimming pools is of great significance due to the non-negligible toxicity and widespread existence of DBPs. However, the management of DBPs remains challenging as the removal and regulation of DBPs is a multifactorial phenomenon in pools. This study summarized recent studies on the removal and regulation of DBPs, and further proposed some research needs. Specifically, the removal of DBPs was divided into the direct removal of the generated DBPs and the indirect removal by inhibiting DBP formation. Inhibiting DBP formation seems to be the more effective and economically practical strategy, which can be achieved mainly by reducing precursors, improving disinfection technology, and optimizing water quality parameters. Alternative disinfection technologies to chlorine disinfection have attracted increasing attention, while their applicability in pools requires further investigation. The regulation of DBPs was discussed in terms of improving the standards on DBPs and their preccursors. The development of online monitoring technology for DBPs is essential for implementing the standard. Overall, this study makes a significant contribution to the control of DBPs in pool water by updating the latest research advances and providing detailed perspectives.