IT MOVES in relentlessly. Attack it, and it scatters and evades you, but the moment your guard is down it silently regroups 鈥� on lampshades and ledges, in corners and crevices. It charges out at you from under your bed. No matter how often you shake a rag at it, dust always seems to have the upper hand.
And that鈥檚 just in your home. Imagine having to look after a larger place, somewhere packed with delicate knick-knacks that are on show day after day, with tens of thousands of people passing through each year. So vexing is the battle against dust that the people who run historic homes and palaces have made it the subject of systematic scientific scrutiny.
Dust poses two big problems for museums and historic buildings 鈥� not to mention the obvious one, that it makes a place look slovenly. First, cleaning it up takes a lot of time and money. Kate Frame, head of housekeeping at Historic Royal Palaces, the organisation that manages five of Britain鈥檚 royal buildings, reckons it takes about 40 hours of cleaning every day to keep the royal dust-bunnies at bay. And all that time ends up costing Historic Royal Palaces more than 拢131,000 each year.
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A more pressing problem is that cleaning precious exhibits can actually damage them. Even the most gentle encounter with a vacuum cleaner can scratch a delicate surface or suck up a few vital threads from an ancient tapestry. Morten Ryhl-Svendsen of the National Museum of Denmark鈥檚 analytical lab in Copenhagen is studying dust deposition on 1000-year-old Viking ships on open display at a museum in Roskilde. 鈥淓very time the ships are cleaned, some bits break off,鈥� he says. And no matter how small the breakage, each represents the loss of a little information about the objects. Though some fragments can be retrieved from the vacuum bag and replaced, cleaning is clearly accelerating the exhibits鈥� decay, Ryhl-Svendsen says.
Several studies launched in the past few years are attempting to put the study of dust on a scientific footing. What is it composed of? How quickly does it accumulate? How damaging is it? And what is the best way to keep it under control?
The conventional view is that dust is blown inside through windows or doors, says Peter Brimblecombe, an atmospheric chemist and dust expert at the University of East Anglia in Norwich, UK. He is involved in a study at London鈥檚 Tate Gallery alongside the National Trust, English Heritage and Historic Royal Palaces, which is beginning to overturn that idea.
The Tate Britain, for instance, wanted to know whether air conditioning helped protect paintings from the ravages of pesky particulates in the air. To find out, conservators placed microscope slides on the top edges of frames of several paintings and left them there for seven days. Some were in older galleries, where ventilation was mainly through doors and skylights; others were in the newer, air-conditioned spaces. At the end of the 9-week study period, the conservators measured the amount of light reflected from the slides to give an indication of how much dust had collected.
To their surprise, the air-conditioned area was far from dust-free. 鈥淚t turns out it was only twice as good as areas that don鈥檛 have modern ventilation systems,鈥� says Helen Spande, a conservator at the gallery. In 2002 Ryhl-Svendsen and his colleague Anette Hjelm Petersen used a similar technique to study the dust on Viking ships. They positioned sticky patches at various locations in and around the open ships, then analysed them using light microscopy, scanning electron microscopy and gas chromatography. Among their discoveries was dust coated with a toxic plasticiser from PVC floor tiles.
Meanwhile, Brimblecombe and his colleagues used sticky patches to collect dust in several British historic houses, including Knole in Kent, Osterley Park in west London and Audley End in Essex. The patches were placed vertically, at 20-centimetre intervals, on walls, curtains and tapestries, and horizontally on bedspreads and floors.
After 8 weeks, the sticky samplers were inspected under a microscope to discover what kinds of particles had been trapped and to work out where they had come from. The researchers also used automated image analysis techniques to calculate how much dust had been collected.
All three studies fingered the same culprit: you and me. Where there were a large number of visitors, dust levels were high. And objects that visitors got closest to were the ones that were most densely shrouded in fluff. Skin flakes and strands of hair contribute to the muck, but the biggest menace turns out to be clothes. 鈥淔ibres just work their way out of woolly jumpers,鈥� says Katy Lithgow, a senior conservator with the National Trust. In the case of the Viking ships, a noticeable proportion of the fibres were thin strands of blue denim from visitors鈥� jeans.
It has been known for some time that people carry a sort of permanent, personal cloud of debris around with them. These investigations seem to indicate that people dump a fair amount of this cloud onto national treasures. Sadly, the very people on whose behalf the dusting takes place are themselves the cause of the problem.
So what is the answer? The electronics and pharmaceutical industries have already developed sophisticated devices such as air showers to de-dust anyone who sets foot inside their premises. It鈥檚 effective, but not exactly what you might expect on a visit to Chartwell or Hampton Court. 鈥淧utting people in boiler suits wouldn鈥檛 enhance their enjoyment,鈥� says Lithgow. 鈥淰isitors have to be built into the whole picture.鈥�
It seems that the best way to protect museums and their contents for future generations to enjoy is to keep the current generation away 鈥� or, at least, as far away as possible. Brimblecombe鈥檚 study found that for each additional metre people are kept back from furniture or pictures, the quantity of dust they deposit is halved. 鈥淭he particles [we] shed don鈥檛 travel far,鈥� he says. At least 2 metres should separate a Tudor chair from a visitor鈥檚 tweed jacket.
The researchers also discovered that the more vigorously people move, the more fibres their clothes shed, which suggests there might be some benefit in changing the way visitors are directed past exhibits. In a stately home for example, people tend to be most active at the beginning of their visit 鈥� adjusting rucksacks, taking off jackets and coats 鈥� so the most precious exhibits should be displayed last. This would have the added advantage 鈥� from a conservation point of view 鈥� that visitors will be getting tired by then and may spend less time admiring the exhibits. And no twists and turns, advises Brimblecombe: 鈥淒esign routes so people don鈥檛 turn corners sharply or walk back and forth.鈥�
It also turns out that almost all the problem dust is shed from our clothes between the shoulders and the waist. Dust kicked up by feet is heavier and usually falls back to the ground. So clear plastic barriers up to shoulder level could cut out a good deal of the dustiness, they say. Ryhl-Svendsen even goes so far as to propose that Viking ships would be best protected if they were entirely encased.
The results so far may not be completely unexpected. But in the next phase of the study, Brimblecombe will begin to look at what happens as dust changes over time from the fluffy floating variety into its more recalcitrant 鈥渃oncreted鈥� self, better known as grime. Can it leave permanent stains? Could it even erode what鈥檚 underneath? It鈥檚 unlikely that the study will call for an immediate halt to all dusting. Although there are some who claim dust can be protective, Brimblecombe says that dusting a lot less may be a better option.
What he鈥檚 really searching for is that fundamental formula for dust busting 鈥� the optimum interval between cleaning that will please not just the marginally house-proud, but also the obsessive-compulsives among us.
Alien dust is different
Skin flakes and clothing fibres are not the only things to be found in your household dust. There are those who believe that evidence of your abduction by aliens could be lurking there too.
William Levengood, a former scientist from the glass industry who now works in a lab at his home in Grass Lake, Michigan, has examined dust from the house of a woman who reported seeing a tube of light come through her ceiling. What he found under a microscope came as a surprise. 鈥淭o my utter amazement, I found these extremely interesting particles, a few micrometres in diameter,鈥� he says. 鈥淭hey were tiny glass-like spheres.鈥� He noticed fissures in the particles, but whereas these would normally result from pressure applied externally, in this case they appeared to have been caused by forces inside the spheres. 鈥淚t鈥檚 extremely unusual,鈥� he says.
Levengood has since analysed dust swabbed from under the bedsprings and above the door frames of people who claim to have been abducted by aliens, and others who say they have not been visited. He says only the dust of alleged abductees contains these telltale glassy spheres.
Levengood, whose most recent publications are on the subject of crop circles, remains open-minded about the possibility of visitors from outer space. 鈥淚鈥檓 not saying I believe in this alien abduction,鈥� he says. 鈥淣or do I disbelieve it. I鈥檓 just looking at it objectively.鈥�