A MAJOR incident at Winsford Lifestyle Centre may have been caused by bleach being manually applied to the pool’s overspill channel, an investigation has concluded.

On March 10, emergency services called a major incident amid fears of a gaseous chlorine leak at the Lifestyle Centre after a number of children began having problems breathing.

Children began coughing, vomiting and complaining of a stinging sensation in their eyes. Ten children and an adult were taken to Leighton Hospital.

An initial investigation concluded that chlorine levels in the pool had been ‘higher than normal’ and could have caused odour and discomfort.

Now, an official investigation has revealed the incident likely occurred when sodium hypochlorite – more commonly known as bleach when dissolved in water – was manually applied to the pool, creating harmful chloramines.

Chloramines can cause breathing problems, headaches and nausea, among other symptoms, and are responsible for the distinctive ‘chlorine’ odour in swimming pools.

They occur when mixed with acids, which are commonly used in swimming pools, and is an indication that free chlorine levels are too low.

The report reveals the water in the pool’s balance tank, which maintains water and chlorine levels, was at ‘low-low’ and the automatic disinfectant dosing system had turned off.

The free chlorine levels in the main pool were recorded as low from the time the pool was first used at 6am and during the whole of the morning of March 10, the report said.

In his report, Mike Dix, Cheshire West and Chester Council’s senior manager, culture and environment, said: “In order to restore the levels of free chlorine in the main pool the Duty Supervisor added the sodium hypochlorite into the poolside overspill channel following Brio’s policies and procedure “Adding sodium hypochlorite to the relatively higher concentration of nitrogenous matter in the balance tank via the overspill channel could create relatively high levels of chloramines in the balance tank.”

Summarising, Mr Dix said: “The presence of the strong smell and the symptoms presented by the children and adults in the pool hall after using sodium hypochlorite in the overspill channel is, however, consistent with the production of chloramines which are known to cause respiratory and eye irritation and nausea at high levels.”

In March, the Guardian reported that chloramines may have formed after chemicals had been hand-dosed into the pool on the day of the incident.

CWAC confirmed that chlorine was manually applied to the pool on March 10, though the new report says it was bleach that was applied.

It states that no other chemicals were used poolside on the day of the incident.

Mr Dix said hand-dosing into the overspill channel is ‘standard practice when free chlorine levels in the pool are low’.

The report concluded there was no breach of Brio’s policies and procedures.

However it recommended that Brio reviews these to ensure they reflect the fact it is now known high levels of chloramines can be created under certain circumstances, which could result in discomfort for customers and staff.