Abstract: Employee #1, a volunteer manager for a neighborhood-owned pool, was preparing to change a chlorine cylinder. The gauges showed that the cylinder was empty, but the shut-off valve was not tightly secured in the OFF position, and while she was removing it from the attached regulator, residual chlorine in the line leaked out. Immediately after the chlorine began to leak out, Employee #1 told the lifeguards to evacuate the area and to call the fire department. Employee #1, who was now experiencing some respiratory irritation, opened the gates at the end of the water treatment shed for ventilation. She was evaluated by the medical response crew, transported to the hospital, kept overnight for observation, and released. She suffered no chronic/acute problems. Employee #1 was not an employee. There were no accident-related violations found.