Model planes are to appear in the sky above Norwich to highlight the scale of invisible aircraft emissions.

Artists Helen Evans and Heiko Hansen will be flying the model planes, which will trail a plume of vapour above the city, during the Norfolk and Norwich Festival in May.

At timely intervals, the models will spray out non-polluting disco fog, to highlight the environmental damage low-cost flights are doing to the world, say the artists.

'It is so cheap now to get a flight anywhere, but at the same time they are bad for the environment,' said Ms Evans. 'They do not have visible emissions except for take-off and landing.

'Pollution used to be very tangible. People know about the London smog. Now we do have air-quality issues, but they are invisible.

'Our project is about making emissions more visible in a very small and humble way. By releasing plumes of vapour at timely intervals, it is hoped people will consider the damage low-cost airlines are causing.'

Ms Evans, 39, who now lives in Paris with Mr Hansen, said: 'At moments, when seen against the backdrop of the sky, it gives the illusion of a real plane flying above the city and leaving a smoky trail behind it.'

Yesterday they tried out a prototype of the planes at the Outcast gallery in Norwich.

The pair are doing a research residency at the University of East Anglia and will be publishing a book about 'man-made clouds' next year. The locations of the planes has not yet been decided and although the artists have plans in the pipelines, they are hoping to find an office block or other multi-storey building.

They were hoping to fly the planes from Westlegate House, HMSO Sovereign House in Anglia Square and Norwich Union building on St Stephens Street. However, all the unused buildings are condemned and cannot be accessed.

The aeroplanes will be suspended on a steel cable, connected between two buildings above the street. A motor will turn a wheel at one end like a cable car or ski lift. The planes release remote controlled emissions at moments throughout the day.

Both Ms Evans and Mr Hansen studied at the Royal College of Art.

If you have a building the pair could suspend the aeroplanes from contact assistant producer Molly Rigg at the Norfolk and Norwich Festival on 01603 877768.

For more information about the artists and their work go to www.hehe.org.

Are you doing something to highlight environmental issues or running an art project in the city? Contact reporter Annabelle Dickson on 01603 772426 or annabelle.dickson@archant.co.uk.