COUNCILS will be urged today not to sell off outdoor play areas to developers, amid claims a lack of childhood exercise is a "health disaster waiting to happen".

Dr Sue Robertson, a GP and kidney specialist from Dumfries, will make the call after becoming worried about the link between childhood obesity and vitamin D deficiency and the decline in the number of children who play outdoors. In Scotland, 20% of children are overweight by the time they start primary one.

She will propose a motion at a British Medical Association conference in London calling on the UK Government and devolved governments to promote outdoor play for children. Delegates will be asked to support the promotion of a "culture of children playing outside in view of the health benefits".

Dr Robertson will also call for governments to "instruct local authorities to stop selling off outdoor play spaces for development purposes and instead invest in the development and maintenance of these spaces to ensure they are safe, stimulating and easily accessible".

She told The Herald: "We just see increasing numbers of young people who are overweight, and there's also an increasing amount of evidence that young people are taking less and less exercise, particularly in the form of free play, and I think this is a huge health disaster waiting to happen as these children grow into adulthood.

"There's obviously many more indoor activities than there were, with games consoles and so on, but also there is less 'free space' for children close to their house or at a safe distance to play freely in as children did in the past.

"There's no doubt we have a sense that more spaces are being used for development and that as towns sprawl, children are getting further and further away from play environments. The spaces that are there seem to be less well-maintained as the councils have less and less money to pay people to maintain them and keep them safe."

Scotland's 32 local authorities have a statutory duty to provide adequate sports facilities for local people.

Any sale of playing fields must be approved by sportscotland, the lead agency for developing sport. If it objects, the Scottish Government can call in and determine the application.

More complex is the issue of areas used for play but not designated as sports facilities.

Dr Robertson said "free play" was as potentially beneficial to children's health as organised sports and activities, particularly given mounting evidence about the health benefits of vitamin D, which is generated naturally in the body in response to sunlight.

"A huge proportion of our Scottish population are vitamin D deficient," said Dr Robertson. "If children play outside, it has been proved that they will not only be less overweight but they will have fewer symptoms of anxiety and depression, and also they will be able to get the vitamin D they need from exposure to the sunshine.

"That's very much an emerging health story – particularly at our latitude. We think vitamin D [deficiency] might be associated with a lot of different illnesses and diseases, but we don't understand the associations as yet."

If the motion is carried at the London meeting, it will be considered at the BMA's annual conference in June. If passed there, it could be adopted as an official policy on which to lobby the governments.

A spokesman for Cosla, the umbrella body for local authorities in Scotland, said: "Local authorities on a daily basis balance complex and competing priorities. Councils work hard to encourage jobs and affordable housing alongside the development and maintenance of high-quality green space."

A Scottish Government spokesman said: "Participation in physical education, physical activity and sport are important aspects of developing healthier and more fulfilling lifestyles for young Scots."