- Pam Dalton, PhD, MPH, experimental psychologist based in Philadelphia, PA
“The idea behind nose blindness is that the olfactory system is designed to detect changes in our environment,” says olfactory scientist and experimental psychologist Pam Dalton, PhD, MPH, who conducts research on nose blindness and scent at the Monell Chemical Senses Lab in Philadelphia. “When a chemical is present for a long period of time—and by long, it could be a minute to five minutes to an hour—the receptors in the nose stop responding to it because it's no longer providing new information.”
"If we have survived breathing in an environment for a few minutes while smelling an odor and nothing bad has happened, we don’t really need to pay attention to that smell anymore—so we stop being able to detect it." —Pam Dalton, PhD, MPH
Essentially, smell is one of the senses that our bodies use to gain important safety clues about our environment—meaning the system is designed to warn us of potential danger. “If we have survived breathing in an environment for a few minutes while smelling an odor and nothing bad has happened, we don’t really need to pay attention to that smell anymore—so we stop being able to detect it,” says Dr. Dalton, “which is nose blindness at work.” And unless the aroma changes in intensity, we’ll stay nose-blind to it within that environment.
Given that many of us are still spending ample time at home—and perhaps more time than was the case before the pandemic—it’s very likely that we’ve gone nose-blind to a variety of scents swirling around our spaces. “In normal times, we go in and out of our home multiple times a day, and there’s a lot of scent dilution that happens with just opening and closing the door,” says Dr. Dalton.
Staying inside (and doing things of smelly consequence), by contrast, allows for more odors to get trapped—particularly in fabrics like upholstery and carpets—and for you to become nose-blind to those stuck-in smells. “If you also don’t have a high-functioning air-filtration system, like one that operates with carbon filters, then it’s easy for these odors to get recirculated within your environment, too,” says Dr. Dalton.
Why certain smells linger
Not all smells are created equally, and particular aromas will be more likely to stick around in a space than others—making nose blindness at home more of an issue for those long-lingering smells. "Certain scent molecules are heavier in terms of their molecular weight, so they’re less likely to be disintegrated by things like ozone light in the environment," says Dr. Dalton. For example, consider the smell of sweaty feet or aged cheese, both of which come from short-chain fatty acids, which have high molecular weights and tend to linger. Same goes for pet odors, which stick to surfaces easily, by way of dander or even urine in the case of cats without great, well, aim.
"Other types of scent molecules are lightweight and very volatile, meaning they’ll diffuse and escape quickly," Dr. Dalton adds. Fishy-odor molecules, for example, are small and dissipate fast—but we’re particularly sensitive to these smells, so we tend to detect them for a while, even if only a tiny bit of the smell actually remains.
How to know if you’ve become nose-blind to smells in your home
The best way to determine if you've become nose-blind is to invite somebody into your home who won’t be afraid to share their honest opinion about whether they can smell something, says Dr. Dalton.
Another idea: To figure out if a particular item reeks, change its context, if possible. For example, if you suspect a throw blanket on your couch smells but can’t detect any odor when you sniff it, take it into another room, and then try again. “Sometimes we get accustomed to smells in a particular space, but if we move them into another place, we can begin to smell them again,” says Dr. Dalton. Relocating the item can help alert you to the fact that you’ve become nose-blind to its smell.
It’s also worth noting that everyone processes smell a bit differently, and when we assign a value to a smell—either good, bad, or indifferent—it can actually change how long we continue to detect that smell before experiencing nose blindness. According to Dr. Dalton's research, when a person thinks a smell is bad, they’re likely to smell it longer than if they thought it smelled good.
In an experiment, she placed three groups of people into rooms with the same smell. She told one group the smell was a botanical extract from a flower, another that it was test deodorant, and the third that it was a chemical that had made certain people feel unwell. “Under those circumstances, the last group of people that were given the warning about the odor being bad were the ones who kept smelling it for significantly longer than the people in the other groups,” says Dr. Dalton. “It’s not that their olfactory systems were working better, but instead, it’s as if they turned up this system in their brains and became more attuned to it.”
How to get rid of smells you’ve gone nose-blind to:
Just because you’ve gone nose-blind to smells in your home doesn't mean guests in your space have. Thankfully, you have options for eliminating potential odors in advance. “We always say, the solution to pollution is dilution,” says Dr. Dalton: Open your windows, open the door, and air things out as much as possible, in order to allow odor molecules to be freed from surfaces and dissipate into the air. Turning on fans can help with this, too, if you have them at the ready.
Another option: Use a home deodorizer—look for that term, as opposed to a home fragrance that just adds a new scent to your space—which typically contain starch molecules that bind with smelly compounds and flock them out of the air, says Dr. Dalton. "Enzymatic cleaners can also degrade malodors on surfaces," she adds, "as their active ingredients form bubbles around the malodor molecules, essentially removing the scent from the air."
Whatever you choose (or don't!), know that once your guests settle in and you start chatting about non-smell-related topics, they’ll likely become nose-blind to any swirling smells, too, with time. In fact, the beauty of nose blindness is that whatever the nose, well, knows, it eventually forgets.
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