Nothing to Sniff At

One of the numerous lingering impacts side effects of the not too-long abated COVID pandemic was the loss of the sense of smell for many people. For those who escaped this side effect it was difficult to imagine how people who could not smell anything may be feeling. For those who were affected, it must have been a really unnerving sensation.

The sense of smell, or olfaction, is the special sense through which smells are perceived. While impairments of the sense of sight or hearing are more apparent in the person with the disability and more evident to others, an olfactory dysfunction affects the person very personally, and less is less noticeable to others.

One of the side effects of losing one’s sense of smell is the losing also the sense of taste or gustation. These two senses are closely interconnected. In fact our sense of smell is responsible for about 80% of what we taste.

Both are chemical senses. The perception of a smell occurs when substances in the air pass through the nose and stimulate the olfactory (smell) nerve. The experience of taste, or gustation, occurs when the taste buds in the mouth respond to substances dissolved in saliva. Without our sense of smell, our sense of taste is limited to only five distinct sensations: sweet, salty, sour, bitter, and the newly discovered ‘umami’ or savoury sensation. But what we call ‘taste’ is actually ‘flavour’–a combination of smell, taste, spiciness, temperature and texture. Much of the flavour of food comes from smell. Thus both the senses–taste and smell–contribute to the experience of flavour. When we are unable to smell we lose much of our ability to experience flavour. Most of us have experienced that when we have a cold and our nose is blocked most foods taste bland. But not many of us have consciously registered that when we are hungry our sense of smell becomes stronger! Think of how all the aromas emanating from a kitchen or bakery start making our mouth water!!

So how exactly does humans’ sense of smell work? This is where the nose and the brain work together. Inside the nostrils are tiny cells, called olfactory neurons, that have long cable-like connections that send electrical messages to a spot at the front of the brain, known as the olfactory bulb. Each olfactory neuron connects with a different neuron in the olfactory bulb, which then sends this information to other areas of the brain. When odours or distinctive smells enter the nose, they travel to the top of the nasal cavity to the olfactory cleft where the nerves for smell are located. The combination of activated neurons generates all the unique smells that we as humans can detect.

The way the brain deals with smells is very different to how it deals with other senses, such as seeing and hearing. For example, we can identify the different instruments playing in a band, or the different shapes and colours in a painting. But it is very hard for us to tell the individual parts of a smell mixture

The brain does more than help us smell, it triggers memories associated with the smell. This is how sometimes a particular fragrance immediately conjures up memories of a person who one associates with that fragrance, or a food smell brings back memories of childhood kitchens and food lovingly cooked and served in the family. Some smells may also trigger sad or unpleasant memories that one thought had been pushed away in the farthest recesses. As Helen Keller said: Smell is a potent wizard that transports you across thousands of miles and all the years you have lived. 

The sense of smell is not just about enjoying the flavours of food or relishing memories evoked by fragrances and odours. This sense is important for our well being. Smell helps us to distinguish good from bad odours. Often we smell stored food to know whether it has “gone bad”. Food that smells over fermented or not as it should is a warning that it may be harmful if ingested. The smell of a “dead rat” (literally) or rotting matter alerts us to the state of hygiene in a particular location. The smell from a gas leak or “something burning” is an early warning system of potential danger.

While we take these smelling tests as a normal part of our daily life, the inability to use smell as an early detection aid can be dangerous for those who lack the sense of smell.

In fact this lack is a medical condition called ‘anosmia’. The term refers to the inability to perceive odour or a lack of functioning sense of smell. Anosmia can be caused by a wide range of factors. The most common reasons are due to upper respiratory or sinus/nasal infections or viral diseases. The condition may be temporary or permanent depending on its cause.

While anosmia is the complete loss of sense of smell, other types of smell dysfunction include: hyposmia, which is the partial loss of the sense of smell; parosmia, which is when the perception of smells becomes distorted, so pleasant smells start to seem unpleasant, or an odour appears to change intensity; and phantosmia, which is when a person believes that they can smell something, but it is not actually there.

Compared with other disabilities, anosmia is a condition that is relatively undiscussed. This leaves a lot of people who are affected by it feeling isolated and lost. This was exactly what Daniel Schein an American, who suffered from congenital anosmia felt. Growing up with anosmia, I never knew anyone else with the disorder and it was just something I accepted and lived with. But I soon learned that there were many people all over the world in the same situation and different groups doing important research. I started Anosmia Awareness as a way to bring together everyone interested in anosmia, encourage research and spread awareness.

Daniel Schein’s awareness campaign was formalized through the launch of an Anosmia Awareness Day in 2012. Now an annual event, the day is marked on 27 February every year. Daniel also runs the website which is a valuable resource for those who are keen to know more about the condition.

The day was not well-publicized initially. However the movement got a boost when a UK-based charity called Fifth Sense joined in supporting the cause. Today this group is dedicated to support and advice people with smell and taste-related disorders, and to making this day an international reminder of the gift that we often take for granted.  


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