Evaluation of cyanuric acid residue in some swimming pools in hanoi and their health risk on swimmers

Abstract

   Free chlorine has an effective disinfectant against contaminants in swimming pool water, including microorganisms and human waste. However, under ultraviolet radiation from sunlight, free chlorine is easily degraded, reducing its disinfection efficacy. To overcome this limitation, trichloroisocyanuric acid (TCCA) is commonly added to maintain a stable concentration of free chlorine and prolong its disinfectant action. During decomposition, TCCA generates cyanuric acid (CYA), a compound that helps stabilize chlorine in water. Nevertheless, the accumulation of CYA at high concentrations can adversely affect human health. CurrentlyAt present, many countries, including Vietnam, have not yet issued technical regulations specifying the permissible concentration of CYA in swimming pool water. According to the recommendations of the National Swimming Pool Foundation (NSPF) USA and the World Health Organization (WHO), CYA concentrations should be maintained below 100 mg/lL to ensure disinfection effectiveness and swimmer safety. The study, conducted at five swimming pools during the swimming season in Hanoi, detected CYA concentrations in two out of the five pools. Using methods such as swimming pool water sampling and laboratory analysis, the study found that Pool P4 had CYA concentrations ranging from 36.28 to 43.11 mg/lSpecifically, pool P4 had CYA concentrations ranging from 36.28 to 43.11 mg/l, which falls within the recommended limits; whereas pool P1 exhibited CYA concentrations ranging from 267.87 to 324.35 mg/l, significantly exceeding the recommended levels and posing potential risks to swimmers' eyes, skin, and respiratory system.