Ever been trapped beside someone on a bus, their perfume so potent that it feels like an assault on your nostrils? You might’ve wondered, “Does she even realize how strong that is?” This brings us to an intriguing aspect of human olfaction: the phenomenon of becoming ‘nose-blind’ – or scientifically put, olfactory fatigue.
Being nose-blind might sound like a downside, especially when someone, let’s call her Perfume-Peggy, seems unaware of her powerful scent. But historically, this olfactory fatigue was a survival mechanism. Imagine our ancient ancestors, their personal scent blending with the environment. Recognizing new odors, like a predator lurking nearby, could mean the difference between life and death.
So, How Does This Work Scientifically?
Deep within our nasal cavity lies a set of cells called olfactory epithelium, connected to the olfactory bulb in our brains via olfactory neurons. At the tip of each neuron, you’ll find a receptor cell. When airborne chemicals, like the fragrance molecules from a perfume, come into contact with these receptors, it results in what’s known as protein-ligand binding. This binding triggers a signal to our brain, culminating in the sensation of smell.
Of the myriad olfactory genes we possess, around 350 are crucial for producing these receptors. Each receptor is fine-tuned to respond to specific chemicals – from the inviting aroma of coffee to the overwhelming notes in Perfume-Peggy’s chosen scent. Contrary to previous beliefs that humans could only discern about 10,000 distinct smells, recent research by Dr. Leslie Vosshall and her team at Rockefeller University suggests we can detect at least 1 trillion different odors! And she believes this number could be even more, given the infinite combinations of odor molecules in nature.
This sophisticated system sometimes needs a break. When an odor molecule binds to our receptors, there’s a surge in the cell’s sodium and calcium levels. This leads to the cell membrane’s depolarization, resulting in an electrical impulse. Over time, repeated exposure can close these channels, leading to olfactory fatigue. In other words, you become ‘nose-blind’ to that particular scent.
How Then Can We “Reset” Our Noses?
You might’ve noticed coffee beans at perfume counters, believed to act as a “nasal-palate cleanser”. The theory is that the strong aroma of coffee – comprising around twenty-eight different chemicals – could potentially reset your smell receptors. However, studies suggest that simply breathing in fresh air could be just as effective.
There’s also the old wives’ tale of sniffing your own skin to reset your olfactory system. While anecdotal evidence abounds, there’s limited scientific backing for this trick.