trichloramine

Trichloramine, or nitrogen trichloride, is a volatile chemical compound with the formula NCl3. It belongs to the chloramines family and forms when chlorine-based disinfectants react with nitrogen-containing compounds. In typical conditions it is relatively unstable and tends to off-gas from water into air. In concentrated, pure form, NCl3 is highly reactive and can detonate if shocked or dry.

Formation and occurrence: Trichloramine forms when chlorine or chlorinating agents react with ammonia, urea, sweat, urine, or other organic nitrogen present in water or on pool surfaces. It is commonly detected as a byproduct in swimming pools, spas, and other facilities that use chlorine for disinfection, especially in areas with limited ventilation or high bather load.

Health effects: Exposure to trichloramine can irritate the eyes, nose, and throat and may provoke coughing or shortness of breath. It can aggravate asthma and other respiratory conditions, particularly with prolonged or repeated exposure. Sensitivity varies among individuals, and vulnerable groups may experience symptoms at lower concentrations.

Management and prevention: Reducing chloramine formation and improving air exchange are primary strategies. Practices include maintaining appropriate free chlorine residuals and pH, reducing nitrogenous sources by encouraging showering before swimming and limiting urine and sweat, and increasing ventilation in indoor pool areas. Some facilities use additional water or air treatment steps to remove chloramines from the environment. Regular monitoring helps keep indoor pool environments within safety guidelines.