EVEN before the bottles in the box marked "fear" are opened, it is possible to smell a small heavy cloud percolating the air: musky, sweet and acrid. In a tiny laboratory in Berlin, Sissel Tolaas, smell provocateur and fragrance developer, is sorting through the concentrated containers of sweat scent she has collected from 16 men from all over the world, and all in a state of fear. She wafts the neck of one bottle in front of my nose. The odour catches me at the back of my throat. Tolaas herself coughs and pulls back. "This is a guy who was into S&M. It is quite powerful. And this bottle is not even open. It's really hardcore." She pulls out another bottle and opens it. The odour is more concentrated but sweeter. "That guy was an alcoholic," she explains.

The smell of fear, Tolaas says, is distinct from that of ordinary sporting sweat. She can recognise it both in its bottled form and on human beings. "I can smell people who have fear," she nods. "Not always, but if I concentrate. I can smell a lot of things. Excitement, for instance. I can smell my daughter when she's happy. It's just about concentration and really focusing." To create her collection of sweat she gave the 16 male donors a device designed to be placed in the armpit whenever fear was felt. These men, who all had "an extreme phobia of other human beings", would then send the sample to Tolaas for analysis and reproduction. Nine of these smells were impregnated into a "touch and sniff" product and painted on the wall in an exhibition titled Fear, shown at MIT and other venues across the world.

Another bottle is wafted in front of my nose. This one is light and airy, like a gentle aftershave. "Nice," I say, surprised at its breeziness. I am planning to wear one of these scents on my way home to Scotland and gauge public reactions. With this in mind, Tolaas warns: "You don't want nice. You need something harder. Are you sure you want to do it? You might not get back to Glasgow. Maybe you shouldn't wear it on the plane."

Tolaas is one of those unique individuals whose work careers through so many boundaries that it is hard to express exactly what she is. An artist? A chemist? A smell educator? Her own definition is "professional in-betweener". Certainly she is an innovator, the first person to use "headspace technology", the system developed by the perfume industry to analyse and reproduce the scent of a flower, to capture the grubbier aspects of "reality": odour of slaughterhouse, stench of subway. In Clean: An Unsanitised History Of Washing, published this month, Katherine Ashenburg describes Tolaas as "an odour artist on a one-woman crusade to lead the smell-blinded' back to the valuable, grounding sense of smell". In today's Western society, which is in thrall to a cult of cleanliness, writes Ashenburg, "smelling someone's real body or allowing your own real body to be smelled has become an intrusion, a breach of a crucial boundary". In this context Tolaas stands out. It seems she puts her nose where few others dare.

For Tolaas it's not just that we are bothered by the smell of other people, but, more crucially that we are terrified that other people might smell us. We fear we might commit that social faux pas of emitting our own odour. "We are scared," she says. "We go round like this." She tucks her arms tightly in, as if glued to her sides, sealing up her pits. "We get scared if we don't put on deodorant. We think, Oh, I'm sweating.' So, what? What is so bad about that? Sometimes, if I come into a situation where I have to use my business card, I go like this." She swipes an imaginary card through her armpit, as if picking up a slick of sweat, and passes it towards me. "You want my business card? This is me."

That this suppression of odour might be denying us a basic connection to our surrounding humanity is illustrated by one of Tolaas's stories. At her Fear exhibition in Seoul, she came across a 90-year-old Korean man standing in front of the smell of her Guy Number 9 exhibit and crying. Asked what the problem was, he said that the last time he remembered smelling sweat was in the Korean-Japanese war. That was the last time he had had that close awareness of the scent of other male bodies and he was moved by it. He was so touched, he asked if he could have a litre of Guy Number 9. Tolaas told him that just 2ml would be all he'd ever need. "We are so distanced from the human body by all these hygienic products. I think this was what he was noticing."

Tolaas's small, immaculate laboratory, whose walls are lined with battalions of chemical jars, feels like a modern-day version of the workshop of the perfumier Baldini in Patrick Suskind's Perfume: a place where all kinds of odd and eccentric experiments might happen. Yet Tolaas has neither seen the film Perfume, nor read the book, whose basic premise, that a serial killer manages to distil the ultimate perfume from the bodies of beautiful women, runs contrary to her belief about smell. "It's so full of clichés. There is no global perfume that works for everyone. I don't believe in this."

Since 2004, Tolaas has worked as a consultant for the major chemical producer International Flavours And Fragrances. Through IFF she gains access not only to the vast collection of potted chemicals that fill her shelves, but also to their laboratories worldwide, allowing her to develop a more global, international view of scent and exposing her to the ways in which odour can be so culturally subjective. In return she provides IFF with what she describes simply as "craziness".

Tolaas, whose father was Icelandic and her mother Norwegian, divided her early years between the two countries, and says smell was not an important factor in her childhood. "I come from one of the most pure parts of the world. In Iceland there's hardly any vegetation, hardly any animals. There's hardly any smell. You have the fish, the geyser, the bubbling of rotten egg."

Her preoccupation with the subject began as a purely conceptual thing. She had been working on art projects related to the weather and started to become increasingly obsessed with the atmosphere and what it contained. Quickly she came to believe that smell was a fundamental and very neglected sense. "This is about life," she says. "If you don't have air you're dead. Throughout your whole life, you breathe every five seconds, 23,078 times a day. And every time, you smell."

Realising that very few people or institutions were seriously studying the subject, she decided to research it herself. From the early 1990s, she began to collect smells, putting together a library of different odours from around the world, bits and pieces of whatever she noticed and storing them in tins: a piece of cloth, garbage, a dog turd, a scrap of fish. When she stopped collecting she had 6723 tins. "The purpose was to see if I could train myself to learn smell as I learned my ABC. Can I train my nose?"

One of Tolaas's ideas is that there are "no good smells and no bad smells". She finds all scents interesting, and has a non-judgmental nose. This didn't arrive by accident. It took seven years of self-training. The initial aim of her research was to see if she could teach herself not to feel any aversion. She wanted to find out if it was possible to view smells without disgust. "I made a box full of smells I thought were very bad and another full of smells I thought were very good. Then, over a period, I trained myself to accept the bad by pairing them with the good. Now I am so tolerant. I never feel sick from a smell. I'll go into situations where other people throw up and to me it's just another smell. My immediate reaction is to think, How can I change this into chemistry, how can I use it?'"

Tolaas points out that much of the disgust surrounding smell is strongly linked to bigotry and racism, and argues that more than anything, we need to cultivate the tolerance of the nose. She quotes George Orwell, who was struck by the way odour is linked to feelings of prejudice and wrote that "the real secret of class distinctions in the West" consisted in the belief that "the lower classes smell". This olfactory prejudice, she believes, is programmed not innate. "It is drummed into us from outside, from industry, from our culture, our education." Given this, she believes, we should make an effort to ensure that our children are not raised with this prejudice. Tolaas does a lot of work with children and her daughter Tara - a slender 11-year-old with a sophisticated nose - is her ultimate guinea pig. "Whenever she says something smells bad, I say, Why is it like that, Tara?' And, in fact, her favourite smells are the worst ones. She comes with the kids from school and she says, Mummy, we would like to smell Slaughterhouse Of Paris'."

Tolaas has tracked Tara since she was a baby, recording her smell at intervals. "She's now going into puberty. And I know her smell at those different stages very well. She also knows my smell. I'll give Tara a scent and say, Is this me?' She'll say, Mummy, there's a little bit too much something in there'."

On the day of my visit, Tolaas is due to hold a meeting about a project to create a model for an alternative environment for the children's department of a Berlin hospital. Tolaas is no stranger to hospitals. Cancer has beleaguered her life. First diagnosed with the disease at the age of 18, she has had it six times, and last year had a major operation to remove much of her right breast and some of her lymph nodes. Fragrance has helped her through these experiences. She recalls the fear she felt going for an MRI scan and how she tried using a series of different smells to calm herself. "You are lying in this box, it's claustrophobic and you're thinking this might change your life. How do you cope? I had a pipe going to my nose, with sage, with naturals, and vanilla. Vanilla is so gentle, so soft, so tranquillising."

It's unfortunate, she argues, that we lack a suitable vocabulary with which to describe odour. "We can render 10,000 smells and yet we only have two words to describe them - good or bad. Apart from that the only language we have is metaphors and the slogans of perfume adverts."

Tolaas herself has not worn perfume for years. Mostly she prefers to use her own sweat, reproduced and concentrated, perhaps modified with one of 20 other molecules she uses to tailor it for specific occasions. If she has a big business meeting, for instance, she might add the smell of money. "When I reproduce my own sweat and put it back on my own body the intellectual and psychological reaction I have to that, to my self, is just unbelievable. It's fantastic. I rediscover myself as a human being."

Sometimes, however, she wears other people's scents. At a small white table, as she prepares a couple of atomisers of male fear for me to take away, she picks up the pot marked New York Guy, sniffs it appreciatively and says: "You could wear this." She herself sometimes wears it at parties. The effect, she says, has been one of confusion. People don't quite seem to know what to make of her, how to compute the feminine visual message with the male smell.

In the end, I don't wear any Fear as I get on the plane. Just sitting in the taxi on the way across Berlin, I feel such nausea from the traces of male sweat I have picked up merely by handling the jars, that in the airport toilets I scrub my wrists clean with copious blots of soap. It's not that I'm worried that my fellow passengers will be offended, but that I might not be able to deal with a flight under this cloud of fear. Even so, washing doesn't quite remove the odour. Each time I raise my hand, it wafts back in front of my nose. When I pick up my mobile phone, it is there in my face. The flight is spent as if nose-pressed against someone's armpit.

Back in Scotland, in the toilets of Glasgow airport, I re-apply the sweat, spraying on the odour of two different men, from atomisers labelled New York Guy and Animalistic. On the train to Edinburgh, no-one seems to notice. When I ask the woman next to me what she thinks of my new perfume, she says: "It's more like an aftershave." Back at home, my partner says that I smell of moss, and the childminder tells me I am quite woody. Both appear to find my smell pleasant, and I start to wonder whether my own distaste for the scent stemmed from the fact I knew what it was.

Slowly, I have come to like New York Guy. As I sniff my wrist, I am reminded of a story Tolaas told me of how one woman used to go into her MIT exhibition on a daily basis, wearing a different lipstick each time, and walk up and kiss the Guy Number 6 Exhibit. "She had some kind of psychological thing about him. She thought if she kissed him she would make him feel less scared."

When Tolaas told me this story, I thought it was crazy, a little improbable. Yet, as I write this, a trace of New York Guy is still there. I smell him again, this damp trembling armpit, and he starts to seem like a person I have come to know; perhaps even to like. Wearing his sweat, I feel some strange kind of intimacy with this man I have never met.