Hygiene, it seems, is back. After years in which it was cool to be dirty, the Severe Acute Respiratory Syndrome (Sars) panic has changed the mood almost overnight. In places affected by the virus such as Hong Kong, surfaces in hotels and public transport are being wiped down every hour. In Singapore, this is considered slatternly.
Here in Britain, the sale of hand-wipes and disinfectants has gone through the roof. I know this for a fact, because I emptied the shelves in Sainsbury's in Clapham, south London. The pharmacy John Bell & Croyden, purveyor of homoeopathic earmuffs to the royal family, told me it had been selling out of face masks every few hours.
News broadcasts have also taken to showing us long, lingering shots of people washing their hands, as the best answer to the epidemic, according to scientists, is something that sounds vaguely familiar: it goes by the name of soap. I must admit that I was expecting something a little more high-tech, involving perhaps genetic modification, some brightly coloured test tubes and a few monkeys with wires attached to their brains.
It's not just Sars. Two weeks ago, a report into the rise of super-bacteria warned us that the wards in some of our best hospitals are crawling with antibiotic-resistant bugs. The report advocates a brilliant new approach - stop me if you'd already thought of it yourself - in which staff will apply detergent to their hands and, if the mood should take them, occasionally change their gloves in between rectal examinations and open-heart surgery.
For most of the past century, none of this clean-freakery would have seemed exceptional. Modernity and cleanliness were seen as inseparable. Antiseptic was the smell of the future. The sheer surfaces and gleaming glass of modernist architecture were deliberately contrasted with the fusty dark and dirty corners of Victoriana.
It went too far, of course. So corrupting and disease-laden was dirt thought by an earlier generation that it had to be purged from everywhere, including the lower bowel. One of the huge vaults at the Wellcome Museum medical storeroom in Kensington is devoted to that most essential tool of early 20th-century hygiene: the enema kit. "Unable to sleep? Feeling lethargic?" ask ads from the 1930s and 1940s. What you needed, they argued, was a glorified bicycle pump up your bottom.
But in the 1960s, being dirty became a way of showing that you had more important things to attend to, such as the class war or a serious drug habit. Washing was a symbol of conformity. By the 1990s, hygiene was considered some sort of compulsive disorder. Designer grunge became all the rage and Swampy and his crusty friends became political pin-ups.
Middle-class parents began to argue that dirt was good for you, with the same fervour as their grandparents had defended cold baths. The rise in allergies, it was said, with some truth, was all to do with kids being too clean. Their immune systems hadn't been exposed to enough grime and infections. "Catch-a-cold" parties were organised so toddlers could swap bugs.
This tolerance for dirt just happened to suit politicians on the prowl for things to cut. Cleaning budgets were slashed, rat populations boomed and London Transport did a passable imitation of Quentin Crisp, spasmodically moving dust around until it didn't seem to matter any more. The result is that public space in Britain is filthy and, given the Sars virus's ability to lurk on lift buttons, potentially deadly.
So maybe we should keep the Sars panic going as long as possible. A dose of paranoia could benefit the space we share. And it might even spur science to come up with a solution to one of life's greatest nightmares - how to get out of a public toilet without touching the door handle.