An excerpt from The Dirt on Clean

The people we encounter walking down city streets or sitting on subways are showered, mouthwashed and deodorized. We have come to expect this. They eradicate all natural smells; then, onto their odourless bodies, they import carefully chosen scents. These people are listening to their private musical repertoire on their iPods, messaging people on their BlackBerrys or talking on their cellphones. The illusion is that they exist in their own individual, hygienically sealed bubbles.

If you had been born only a couple of hundred years ago, you would have regularly slept in the same bed with your family or co-workers or fellow guests at an inn, emptied your bowels at a public latrine with no dividers between you and the other users, and might expect to be buried in a mass grave. According to the cultural critic Ivan Illich, it wasn't until 1793 — when the French Revolutionary document "The Rights of Man" championed the right to privacy — that we took a radical step toward sleeping in our own beds and, ultimately, toward dignity.

Privacy and dignity are good things, but it looks as if North America, especially, doesn't know where to stop. Perhaps above all, it's about control: To smell like a body — which alters on its own with time, physical exertion, anxiety and climatic and hormonal variations — demonstrates that we're not completely in charge, something we increasingly expect of ourselves. As more of the world spins out of control, it seems there is a greater drive to manage what we can, however pointless it may be.

Fears about disease are unquestionably exacerbating our twenty-first-century preoccupation with hygiene, whether the disease is the Norwalk virus, bird flu, SARS, another new disease called community-associated methicillin-resistant Staphylococcus aureus or problems associated with the bacillus E. coli. In 2002 and 2003, SARS struck 8,096 people and killed 774. Forty-three of those deaths occurred in Toronto, more than anyplace outside Asia, and that taught Torontonians in short order the virtues of face masks, Purell and handwashing.

According to Vincent Lam and Colin Lee, Toronto emergency-room doctors and the authors of The Flu Pandemic and You, those straightforward, low-tech practices are about the only hygienic steps that might protect us in the next epidemic or pandemic. Get a flu shot by all means, they say, exercise caution with live birds and cook turkey and chicken well. But during a pandemic or even a normal flu outbreak, wash your hands often and properly, cover your face when sneezing or coughing, and keep a distance of at least one metre from sick people. If you're taking care of a sick person, wear gloves and a mask.

For normal life, the one hygienic measure Drs. Lam and Lee advise is handwashing, to protect ourselves and others from the spread of germs. If you're a farmer or a manual labourer — jobs with lots of contact with the ground and potential for cuts — or if you play contact sports, washing your body could prevent organisms from entering through a "portal of entry," a cut or a microcut. Otherwise, as far as health is concerned, the most you have to fear from not washing anything but your hands is skin problems, such as fungal infections.

Charles Gerba, a microbiologist at the University of Arizona who writes and broadcasts as Dr. Germ, agrees that the only parts of the body that need washing for serious health reasons are the hands, but he stresses the wily stubbornness of the thousands of microbes that regularly coat our hands. "Microbes never give up," Gerba says admiringly. "They adapt and they follow our new habits."

He itemizes some of our new habits in the age of information: We spend most of our time in an office, surrounded by electronic equipment that loves to collect germs, where the janitors are told not to interfere with our personal space — that is, not to clean our desks. We travel more and in enclosed spaces such as airplanes, where the toilet will be used by an average of 50 people per flight and is exceptionally germy. And by travelling, we spread diseases all over the world.

Although Gerba says "we have to reinvent hygiene because our world has changed so much," his mantra is an ancient one: clean hands, clean hands, clean hands. He washes his own whenever he leaves his desk, when he goes to the bathroom, after he teaches. When asked, people in movie theatres swear they washed their hands in the restroom, but Gerba and his gimlet-eyed researchers say only 65 percent do, only half of those who wash use soap and only half of the ones who use soap wash long enough; it should be for 15 to 20 seconds. By contrast, he says, to get to a sink in the restroom at a sanitarians' conference, "you have to wait in line." We spoke on the phone, and just before we hung up, I asked Gerba if he would have shaken my hand if we had met in person. "Sure, unless you had a cold," he said, and then paused for a beat. "And after we shook hands, within a few minutes I'd be looking to sanitize my hands with an alcohol gel."

Charles Gerba denies that he's afraid of germs, because, he says, he knows where to find them, and his basic message is a sensible one. But, with his gleeful counts of germs on sinks and fecal bacteria in clean laundry, he is contributing to the anxious sense that we live in a world populated by billions of unseen enemies.

We all know people who go to extraordinary lengths never to shake hands or touch a tap in a public washroom, and whose cupboards are filled with antibacterial soaps. Inventions that address their fears are multiplying. One new product, a plastic box to be installed above the doorknob in a public toilet, sprays a disinfectant mist on the knob every 15 minutes. (However, Gerba says, "Never fear a doorknob." Unlike a sink, it is not moist, and moisture supplies the most hospitable breeding ground for germs.) Another innovation, the SanitGrasp, replaces traditional door pulls in restaurants and other public places with a big U-shaped object that allows the door to be opened by a forearm.

The list of these new products stretches from the plausible to the wilder shores of paranoia. You can buy a portable subway strap so your hands never have to come into contact with the overhead bar, as well as a strip of vinyl that covers supermarket cart handles. You can store your toothbrush in a $50 holder that kills germs with ultraviolet light.

People who were once normally hygiene-conscious are behaving more and more like mysophobes (the technical term for those with an inordinate fear of germs). Others whose horror of germs was considered seriously eccentric, such as the obsessive-compulsive TV detective Monk or the television host Howie Mandel, now seem closer to the norm.

A decade ago, the editorial writers at a large Canadian newspaper were amused when the germ conscious editor-in-chief urged them to write an editorial against shaking hands. (He suggested crossing your arms and nodding instead.) The editorial never appeared. It's doubtful that the editor's suggestion would strike them as outlandish or exaggerated today.

On a very real level, germs concern us because the world has become a significantly more perilous place of late. In recent years, many normal activities, such as eating beef and chicken, travelling on public transit and being treated in a hospital, have turned out to be extremely dangerous in certain places. Arrogantly and ignorantly, we assumed that epidemics such as the Spanish flu of 1918 could not happen again. SARS proved us wrong, and now we dread bird flu or a yet unnamed pandemic. Our fearfulness is heightened rather than lessened by the abundance of information and misinformation available at our fingertips on the internet.

On a more symbolic level, since September 11, 2001, we know that we live in a world that harbours deadly, hidden dangers; terrorists are like germs in that way. The American writer Allen Salkin asks, "Is it only a coincidence that the same places where Americans most fear terrorism — airplanes, schools, mass transit, water supplies and computers — they also fear germs?" Probably not, and what at least some of this overwrought avoidance of germs really demonstrates is our wish to be protected, to be safe in a world that seems increasingly unsafe.