Thirteen six-year-old children and fourteen adults were taken to hospital on the morning of Wednesday 11 November, following a chlorine gas leak at the Kaisari Schools in Koropi. All the children were discharged on the same day and the adults are out of danger, according to mesogianews.gr.
What happened?
The incident occurred at around 10.30 am on the school premises at the junction of Lambtron and Lysimachou Streets, whilst a maintenance crew was carrying out cleaning and maintenance work on the swimming pool. According to the school management, the strong odour was caused by an ‘incorrect mixture’ of materials in a special bin used for cleaning the filters and chlorination. The owner of the schools, Ilias Kaisaris, clarified that the incident did not occur in the pool water, that safety protocols were followed and that the area is now safe.
The 13 children were taken by EKAB ambulances to the ‘Panagiotis and Aglaia Kyriakou’ Children’s Hospital, where they underwent paediatric and ENT examinations. They were asymptomatic; five were discharged immediately after their examinations, whilst the rest remained for a few hours for observation. The 14 adults – staff and other people present at the site – were examined at the ‘Sotiria’ Hospital. Among them were the two swimming pool maintenance workers, who had initially gone to the Health Centre.
Evacuation and search
The primary school and the nursery were evacuated as a precaution. Nine firefighters with four vehicles and a team from the 1st EMAK attended the scene, which located and removed a container of hydrochloric acid stored near the swimming pool.
The owner of the company responsible for maintenance and the two employees were taken into custody. According to Naftemporiki, the owner was initially arrested but was subsequently released on the verbal orders of the public prosecutor. The authorities are investigating how the incident occurred.
Why this affects our schools and homes too
Children from all over Eastern Attica attend the private schools in Mesogeia, including some from Spata and Artemida. The accident occurred during a lesson, whilst a work crew was handling chemicals and the school was full of pupils.
The mechanism is the same as that which causes accidents in the home. When a chlorine-based product, such as bleach or swimming-pool chlorine, comes into contact with an acid, such as hydrochloric acid or limescale removers, chlorine gas is released, which irritates the eyes, nose and lungs. Mixing bleach with ammonia is just as dangerous.
If it happens at home or in the block of flats’ swimming pool:
- Go out into the fresh air immediately and keep children away.
- Open doors and windows only if you can do so without re-entering the room.
- Call the Poison Control Centre on 210 7793777, which is open 24 hours a day, or 166 if anyone is having difficulty breathing.
People with swimming pools store chlorine and pH adjusters separately and do not use the same container for two different products.
Source: mesogianews.gr and Naftemporiki, 11 November 2026, with information from the schools’ management and the Fire Service.
