In what is probably the biggest spring clean ever, they are abseiling from the roof of the Millennium Dome to get stuck into some serious dusting and polishing. Asthma and vertigo sufferers need not apply.
Everything in the 150ft high structure, from the once-white interior canopy to the supporting cranes and the huge ventilation tubes, is caked in a thick, well-settled layer of dust.
The cleaners, who are currently involved in tests to identify the best dirt zapping techniques, are rapidly becoming the most highly skilled and acrobatic cleaning operatives in town, removing stubborn stains and bringing a sparkle to the metalwork across the roof.
The Dome's grubby state is, according to those overseeing the pounds 758m project, the unavoidable consequence of spending the first seven months of its life as a vast indoor building site.
While the outer canopy has a "self-cleaning" coat of Teflon, the inner layer is made of porous fibreglass-weave cloth, designed to alleviate problems of humidity, condensation, acoustics and ventilation.
Dirt from the earth floor and concrete drilling, combined with diesel fumes from construction vehicles and minute metal particles from welding activities, has produced a heavy duty dust, which has penetrated the inner lining.
According to Robert Torday, spokesman for the Dome's architects, Richard Rogers Partnership, this was not entirely unexpected, though the idea of providing a protective covering for the lining was ruled out early on the grounds of cost.
However the cost of the clean-up operation has been budgeted for within the overall expenditure and Mr Torday is confident it will be completed before the handover to the Millennium Experience on 30 September. Now that most of the large scale construction - on the central arena and the skeletal work for the 14 zones - has been completed, tests are underway to find the cleaning fluid best suited to the job.
The plan is to work loose the dirt and suck it up with an industrial vacuum cleaner. Already certain sections of the roof resemble a before- and-after television advert.
Scrubbing the ceiling clean for the Millennium will, eventually, be done by a team of three or four men. Sadly, they are likely to forgo the glamour of high wire cleaning in favour of working from the ground up on cranes and cherry pickers.Reuse content