A few years ago Dr Krati Garg, an oral surgeon in Melbourne, was in the operating room about to start working on a patient when she told the anesthesiologist she could smell sevoflurane.

Sevoflurane is the anesthetic gas used to sedate — and hold — patients during surgery. Ingested via a tube that is placed in the throat, in large quantities, its bitter odor may be noticeable, but traces are largely indistinguishable.

No one else in the room could feel it through their masks, but the anesthesiologist, who had worked with Garg before and knew his sensitive nose, checked the fit of the tube, discovering a small leak and the need for adjust the gasket.

It’s not uncommon for Garg to smell things that other people can’t. She notices the smell of the dirt before it’s about to rain and at home with her husband she’s all too prone to throw away food she thinks smelly, often telling him, “It’s probably better than you taste and tell me if it’s extinguished or not, because I could throw it away even without it extinguishing.

Growing up in India, she was known in her family as having a super sensitive nose, just like her grandmother. She would amaze her mother when she came home from school and was able to accurately describe the foods and spices used in the curries cooked in her absence.

Certain smells gave her a strong aversion – even traces of a particular rose-scented syrup, commonly used in milkshakes in India, set her back. The body odor of a private tutor her family had hired to help her with physics was so disconcerting: “I couldn’t concentrate at all…I was just trying to stop, catch my breath. And then I looked at the clock. After a few months, I said to my mother, “Look, I can’t sit down. And we had to let him go.

Although figuring out that she has an enhanced sense of smell has been an “ongoing process” throughout Garg’s life, this year she began to become more curious about the skill. Working in the health sector in Melbourne, she was regularly tested for Covid-19, but noticed she was also ‘unknowingly’ running her own early warning testing system, constantly checking her sense of smell. (Loss of smell is a symptom of Covid infection.) After reading up on the subject, Garg came to the conclusion that she might be a “super-smeller” – a rare, medically known condition. under the name of hyperosmia.

Dr Leah Beauchamp, a neuroscientist at the Florey Institute of Neuroscience and Mental Health in Melbourne, says individual ‘olfactory acuity’ – our ability to smell – is highly variable and altered by genetics, age, gender (women have a stronger sense of smell) and even mood. Our sense of smell happens via a complex process, where an odor molecule enters the nose and hits a piece of tissue – ‘essentially where you get your Covid test’ – from where electrical impulses travel to various brain regions for interpretation.

Not much is known about those at the outer limits of olfactory ability – it’s rare and subjective, making it difficult to measure. According to Beauchamp, it’s theorized that hyperosmia could be biological — changes in hormones and electrolytes associated with medical differences, like pregnancy or Lyme disease, are known to increase sensitivity to smell — and it can also be learned; a sommelier, for example.

One of the most extreme cases of a super-smeller to emerge in recent years – currently being investigated in the UK – is a Scottish woman who noticed a certain “musty smell” on her husband in the years preceding his diagnosis of Parkinson’s disease. It wasn’t until she walked into a support group for people living with Parkinson’s that she realized the smell was common in their home. “Somebody with that kind of sharpness is basically off the charts,” Beauchamp says. “But you get variability in humans. This is how biology works.

For Beauchamp, it is the absence of smell that offers the most intriguing fields of research. “Smell is a great opportunity for us to access the brain…People think smell is all about the nose, and obviously the nose is important, but it really gives us an indication of brain health. “

The Florey Institute has a number of projects investigating olfactory deficits, including one examining why a cohort of people in Melbourne still have no sense of smell up to 12 months after recovering from Covid.

It’s unlikely someone like Garg will ever receive — or need — an official diagnosis of hyperosmia. Beauchamp says that unless it’s “disruptive day-to-day functioning…they wouldn’t need to have it treated.” Garg says that just being aware of his abilities is enough for him. “I almost feel empowered in some ways that I have that little extra strength or tool.”

Being a super-scenter means she sometimes has to take evasive action, such as “staying away from a particular group of people because someone’s wearing a really strong scent at a party.”

It also means navigating intense memories. Unlike the other senses, the area of ​​the brain that processes smell receives information directly from the part of the brain associated with memory, the hippocampus. For Garg, a certain smell of “wetness” brings her back to the stressful experience of having her house flooded as a child; conversely, the smell of petrol, which she “likes”, overwhelms her with nostalgia for her childhood in India.

“There are people who come and fill it up for you and you just sit in the car with your windows down, or you’re on your two-wheeler and you can smell it with the dust and everything.”