Human error is being blamed for a chlorine leak at a Derbyshire health club which led to a number of people being taken to hospital with breathing problems.
Clifford Health Club and Spa said the leak in January happened after staff had failed to follow correct procedures.
It said there had been a build-up of dry chlorine in the pipework of a hydrotherapy pool which was undergoing maintenance.
Erewash Borough Council says its investigation into the leak in Long Eaton is continuing.
Emergency services were called to the centre in Regent Street after reports of a chemical leak on 7 January.
Derbyshire Fire and Rescue Service said 27 people had been exposed to chlorine and 10 were showing symptoms relating to exposure.
In a newsletter sent to members, an official at the health centre said its investigation found "one or two staff members out of our large operations team had diverted away from their signed and documented training and had been putting chlorine into the wrong part of the pipework which caused the chlorine build up in the dead leg".
It adds that it goes "way over and above every single day and night over the recommended cleaning procedures at a great financial cost to ensure the pools are safe for use".
At least four people were taken to Queen's Medical Centre in Nottingham for treatment after January's incident, including Enid Hollingworth, 71, from Chilwell in Nottinghamshire.
She described how she was suddenly unable to breathe and felt her "lungs burning".
Mrs Hollingworth has told the BBC that almost four months on, her breathing has only just returned to normal and she has been told she needs surgery on her eyelid as a result of the chlorine leak.
