A malfunction at a Tennessee apartment complex's automated chlorine injection system prompted a hazardous materials response July 29 after elevated chlorine levels developed inside the property's indoor pool house, sending one person to a hospital and forcing the pool's closure.

The incident occurred around 8:45 a.m. at The Reserve at Mountain Pass Apartments, according to the Chattanooga Fire Department.

Fire officials said a malfunction with the pool's chlorine injection system caused chlorine levels inside the pool house to rise to hazardous levels. Several people who inhaled chlorine vapors were evaluated at the scene, and one person was transported to a local hospital for further evaluation. No serious injuries were reported.

The Chattanooga Fire Department dispatched a significant hazardous materials response that included Special Operations, HazMat 1, Squad 1, Engine 14, Battalion 1, Ladder 5, Squad 19, Ladder 21, and Engine 9.

After securing the area, firefighters determined the incident was related to a mechanical issue with the pool equipment, according to the department. Officials did not identify the specific component that malfunctioned or release additional details about the chlorine injection system.

The apartment complex's pool and the affected pool house were closed while repairs were completed and the system could be verified safe for operation. Publicly released information does not indicate the type of chlorination equipment involved or whether the malfunction originated with a feed pump, controller, sensor, or another component of the automated chemical feed system. Officials also have not said whether the incident involved a liquid sodium hypochlorite feed system or another form of chlorination.

Unlike many chlorine exposure incidents that result from incompatible chemicals being mixed, fire officials consistently described this event as a mechanical malfunction involving the pool's chlorine injection system rather than a chemical handling error.

As of press time, the Chattanooga Fire Department had not released an incident report providing additional technical details on the equipment failure or the repairs required before the facility could reopen.