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Kai Zhao, a professor of nasal physiology at Ohio State University’s department of otolaryngology, wears a pair of nasal plugs.
Kai Zhao, a professor of nasal physiology at Ohio State University’s department of otolaryngology, wears a pair of nasal plugs. Zhao tested the plugs, made of foam earplugs with a straw embedded, to see if they could help people with smell dysfunction better perceive and identify odors. [Allie Vugrincic | WOSU]

Ohio researchers develop ‘glasses for your nose’ after an uptick in cases of smell loss

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COLUMBUS, Ohio (WOSU) — In the throes of the pandemic, people started noticing something odd: an uptick of negative reviews of scented candles, claiming they had no fragrance. The trend line of the bad reviews coincided with spikes in COVID-19 cases. That’s because one of the symptoms of COVID is smell loss.

As of Sept. 2024, about 1 in 8 Americans over the age of 40 have measurable smell dysfunction, according to the National Institute on Deafness and Other Communication Diseases.

“Especially after COVID, there’s waves of patients with different smell dysfunction. And actually, there’s currently no effective treatment for that,” said Kai Zhao, a professor of nasal physiology at Ohio State University’s Department of Otolaryngology – Head and Neck Surgery.

So, Zhao decided to make one.

The science of smell

Smell dysfunction can be triggered by head trauma, cancer, or infections. In general, it’s caused by damage to the olfactory neurons, located at the upper back of the nasal cavity. We perceive smells when odor particles bump into and bind with those neurons. Zhao estimates only about 10% to 15% of particles actually reach that region, with the rest getting lost in the cavity.

Kai Zhao explains how we intake odor particles and perceive smell with a poster near his office at Ohio State Eye and Ear Institute in Columbus.
Kai Zhao, a professor of nasal physiology at Ohio State University’s department of otolaryngology, explains how we intake odor particles and perceive smell with a poster near his office at Ohio State Eye and Ear Institute in Columbus. [Allie Vugrincic | WOSU]
“So, every breath only a few particles actually get into this region where they have the chance to trigger smell,” Zhao said.

Zhao thought that getting more odor particles to that region would improve people’s ability to perceive and identify smells. He tested two devices on over 50 healthy people and over 50 patients with smell dysfunction.

Zhao first tested a swimmer’s nose clip. The clip is meant to narrow the inside of a person’s nose to create a tunnel that pushes odor particles right where they need to go.

Then Zhao tested a new device that uses an angled straw pointed right at the olfactory region.

“It’s basically made of foam ear plugs, but it has a straw embedded or channel embedded that’s diagonal,” Zhao explained.

The impacts of smell loss

Losing the sense of smell has serious impacts on a person’s life. Smell loss impacts people’s safety and their ability to taste, Zhao said.

Josh Lieb of the Columbus suburb of Pickerington knows that first-hand. He lost his smell and taste when he contracted what he thought was a mild case of COVID.

“I was eating breakfast, and I realized I couldn’t taste my breakfast or smell anything in the room,” Lieb said.

He thought his smell loss would be temporary – but it’s been four years.

“When you eat you just eat based on texture. …You get like a sense of things that are in – that you think are in the room with you,” Lieb said.

Lieb tries to stay positive, but he admits he misses certain tastes and smells. He said he still has a “feel” for things like chemicals in his nose. He mostly depends on his wife, however, to let him know if food has gone bad or if there’s smoke or a gas leak nearby.

Lieb was not part of the Ohio State study, but he’s tried lots of things to get his smell back, including smell retraining – repeatedly smelling the same scents in the hopes of establishing a memory of that smell and stimulating the olfactory system – and multivitamins. Lieb is now looking into more experimental treatments, but he said he’d also be willing to try smell aids like Zhao’s nasal plugs.

There are promising results

Zhao’s study found that both devices did help.

Those with smell dysfunction could identify, on average, one more sm

Reporter Allie Vugrincic looks at the camera with the yellow nose plugs in.
Reporter Allie Vugrincic tried out the plugs. [Allie Vugrincic | WOSU Public Media]
ell with the smell aids than without.

Only Zhao’s handmade nasal plugs seemed to help patients with COVID-related anosmia. Zhao thinks that might be because those patients have more significant smell loss and need a more direct enhancement of airflow.

The only group that wasn’t helped at all by the smell aids were people who already had near-perfect smell.

With all that in mind, I decided to try out the smell aids. I started with the swimmer’s nose clip. I slid it over the top of my nose and fussed with it until it pinched near the nostrils.

Zhao scraped off a scratch-and-sniff card and passed it to me. He used the scented cards to test patients with smell loss in the study. The goal was to correctly guess the smell – which I couldn’t do on the first try.

“It’s like – is it flowers?” I asked Zhao.

“Nope,” he said, with a laugh.

Despite my average sense of smell and below-average scent-deduction skills, the clip did seem to make a difference. With it on, the card smelled more vibrant.