A dangerous gas alert has closed a primary school on Portland.

Pupils were told not to return to Grove Infants School after high levels of the colourless, odourless radioactive gas radon were detected in parts of its building.

Around 70 children were hastily relocated to two classrooms and a school hall at St George’s Primary School at Easton.

It is hoped that the contaminated school will reopen after half term in early November. In the meantime emergency work is being carried out to ventilate the building in Grove Road.

Radon can cause lung cancer if it is inhaled over a period of time.

Headteacher Jane Hurdiss of Grove Infants School said it was ‘all a bit of nightmare’ but they were lucky St George’s could accommodate their 24 Little Stars reception children and 46 pupils.

The alert followed routine radon testing by Dorset County Council at Grove Infants, St George’s School and Royal Manor Arts College.

Results showed Grove’s radon levels exceeded the Health Protection Agency’s ‘action level’ for a workplace and an emergency governors’ meeting saw members vote unanimously not to reopen the school until levels had been reduced.

Mrs Hurdiss said: “The risks of radon are very long term and accumulative but it can contribute to lung cancer.

“The children are fine but I was concerned for the staff who have worked there for years. Any sort of risk isn’t worth it.

“It’s all been a bit of a nightmare but we’ve been really lucky to get accommodated all together at a large school close by.

“The children have seen it as an adventure, they only had two closure days while we moved everything over from the school.

“Obviously behind the scenes there’s been a lot more work for staff, governors and myself.”

Mrs Hardiss thanked St George’s and Royal Manor Youth Club, which is accommodating the after-school club, her ‘magnificent’ staff and supportive school community. Work to install large extractor fans under the school floor will get underway next week.

Administrative staff have remained at Grove school in a log cabin to act as a link for parents.

A meeting will soon be held for parents to question representatives from the Health Protection Agency and local authority and possibly a radon consultant.

Deputy head at St George’s, Jo Luxon said: “It was quite a sudden emergency. We were called following a governors’ meeting because they obviously felt uneasy about entering the premises until it was sorted. We have a bit of extra space so we said we could fit them in our activities room, learning centre and small school hall.”

A Dorset County Council spokesman said the radon testing was part of routine health and safety assessment of school premises.

The results for Grove School on Portland showed levels matched ‘many workplaces and schools across the country’ and established procedures were carried out to limit risk to staff and pupils, including surveillance monitoring and remedial work to reduce the levels as quickly as possible.

The spokesman added: “The Health Protection Agency’s (HPA) advice is that there is no need for alarm or to remove children from school and that the routine should continue as normal.

“However, governors of The Grove took the decision to relocate the children to allow the work to be completed more quickly.”