Emergency services took 26 people to hospital on Wednesday after suspected chlorine gas leaked at a private school swimming pool in Koropi, Greece.
Thirteen pupils aged six, comprising eight boys and five girls, were transported by ambulance to the Aglaia Kyriakou Children's Hospital in Athens for medical examinations. Doctors confirmed that none of the children suffered serious health complications, with five discharged home later in the afternoon while eight remained under observation.
Another 14 adults also required medical care following the chemical release. Twelve adults were admitted to the Sotiria Hospital in Athens, while two others were transferred from the Koropi Health Centre, with medical staff reporting that none had sustained serious injuries.
Emergency response at Koropi school
Paramedics from the National Center for Emergency Care, known as EKAV, deployed multiple ambulances to the campus after the gas release occurred. Teachers and parents accompanied the six-year-old pupils in the ambulances as they travelled to the pediatric hospital in Athens.
Before transferring the patients, EKAV emergency coordinators consulted specialists at Greece's Poison Information Centre. Toxicology experts advised dispatchers to send all exposed children and adults to hospital for preventive screening and respiratory observation.
Koropi is a commercial and residential municipality situated in East Attica, roughly 16 kilometres southeast of central Athens. The town sits on the Mesogaia plain and is home to several educational complexes, athletic facilities, and light industrial estates.
Firefighters remove hydrochloric acid container
Emergency crews completed an operation on Wednesday to remove a container of hydrochloric acid from a storage area near the school swimming pool. The Hellenic Fire Service said its operations centre received the initial emergency alert at approximately 10:20 am.
Nine firefighters operating four emergency vehicles from the local Koropi Fire Service responded to the scene alongside a specialized team from the 1st Special Disaster Management Unit, known as EMAK. Technicians from the specialized unit secured the acid container and moved it to a safe location away from pupils and staff.
The 1st EMAK division operates as the elite rescue and disaster management brigade of the Hellenic Fire Service, trained specifically to handle hazardous material spills, chemical contamination, and complex rescue missions across the Attica region.
Hospital treatment and respiratory observation
Initial reports indicated that the affected pupils and staff inhaled fumes, likely chlorine, generated by chemicals stored for the operation of the swimming pool. Inhaling chlorine gas causes immediate irritation to the respiratory tract, eyes, and throat, though symptoms typically resolve quickly with prompt medical intervention.
The Panagiotis and Aglaia Kyriakou Children's Hospital, located in the Goudi district of Athens, is one of the leading pediatric hospitals in Greece, housing specialized units for urgent child care. Sotiria Hospital, also situated in Athens, serves as the country's central referral facility for chest diseases and respiratory conditions.
Swimming pool operators routinely use hydrochloric acid to control water pH and prevent mineral scale in filtration systems. However, accidental contact between acidic solutions and chlorine sanitizers can trigger rapid chemical reactions that produce toxic chlorine vapor.
Medical evaluations continued on Wednesday afternoon for the eight children remaining at the children's hospital and the adults undergoing diagnostic checks at Sotiria Hospital. Authorities confirmed that the chemical container had been secured and that no severe medical complications had been reported.
