VULNERABLE children being treated in Scotland's new £842m hospital were unable to use the outdoor play area for months because of health and safety concerns.

Use of the roof top garden in the specialist unit on the Queen Elizabeth University Hospital site had to be banned amid fears it was dangerous for patients and people walking below.

It was among a series of health and safety concerns described in a report about the department, which treats five to 12-year-olds from across Scotland with severe mental health problems including anorexia and self-harm.

The report also revealed an alarm system to help staff get back-up if bad behaviour erupted had not been installed months after the hospital opened and this meant the unit could not admit any children with behaviour problems.

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Staff were also concerned the sprinkler system could be activated through-out the ward if a child threw a shoe or similar object at the ceiling.

The report was written by the Mental Welfare Commission who visited the National Child Inpatient Unit, in the new Royal Hospital for Sick Children at the Queen Elizabeth in October.

Their recommendations have now been dealt with - the garden and alarm issues were rectified in January - and NHS Greater Glasgow and Clyde say parents and carers are enjoying the new "state of the art" facilities.

However, minutes from a health board meeting in November suggest some concerns about the facility had been raised 12 months earlier, before it opened. The minutes say: "The fault lay with the specification, design and sign-off process".

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Known as Ward Four, the unit is the only specialist inpatient service for children with severe mental health problems in Scotland. The service was originally based in converted nurses accommodation at Yorkhill. There patients, who tend to have an initial stay of six weeks, had an outdoor play area. Last June the service moved to the top floor of the new children's hospital although the problems with the roof garden and alarm system were known.

When the MWC visited they found although the ward had six beds it was able to accept two overnight patients (and some day patients) amid the health and safety issues.

The report said: "...the ward in its current state is deemed unsuitable for children presenting with significant behavioural difficulties. Given the national status of the unit and the frequency of behavioural disturbance in the catchment population of children that the unit serves this state of affairs cannot be seen as acceptable."

The report also said the behaviour alarm system "would be standard in any mental health inpatient setting" and its absence was "a serious failing."

For more than six months children who could not be admitted to Ward Four because of the restrictions were treated on an outreach basis.

When the MWC visited the ward, parents praised the staff but expressed disappointed the outdoor play area was out of use.

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According to the report concerns about this roof garden "relate to the safety of the children using the play space and their inappropriate access to vented spaces (gaps) in the exterior walls which could prove dangerous to the children in certain circumstances." It continued: "There are also safety concerns relating to the general public who might be injured by articles thrown by the children from the play area down to ground level four floors below."

The MWC staff were also told locks in some corridor areas were "not fit for purpose " and there was a risk children could bypass certain mechanisms and "be able to lock themselves within certain areas."

In addition a "screening room" where children can be discretely observed did not appear to be in line with the dimensions originally planned for the ward, according to the report.

The MWC made eight recommendations and required an action plan within three months.

Clinical psychologist Julie Metcalfe, who is clinical director for the region's child and adolescent mental health service, said some of the issues had only emerged once staff moved in. She added: "The staff did contribute to the design of the unit. It was collaborative, but there are aspects of it in the actual build where we have gone back and said, 'that's not what we wanted'. We have covered those now."

Sophie Pilgrim, director of Kindred Scotland - which supports families including children with additional needs, said it was good the recommendations had been addressed but added that it is "difficult to understand why a ward for children with severe mental health problems would be designed with so little access to outdoor play". While additional play parks are being built for the entire hospital, she said access to these could be problematic for distressed children. She said equivalent facilities in England had been "designed to allow maximum access to outdoor space and this is clearly regarded as a therapeutic benefit."

In a statement NHS GGC said: "The design of the new unit was a process carried out over a number of years and when it opened in June, a number of modifications were identified to further improve this excellent facility. All these modifications have now been implemented."