Reawakening the Invisible Sense: Turning Everyday Smell Testing into Longitudinal Sensory Data — for Scientists and the Individual

By Mindy Yang

The card is silent until you touch it. Fingertips on paper release a whisper of mint, citrus, something more elusive—the ghost of a childhood kitchen. I hesitate, trying to name what my brain knows but cannot place. This isn't just smelling; it's testing a sense we've long ignored.

At the World Taste & Smell Association, we've spent years witnessing what happens when the invisible sense flickers or vanishes. Smell forms first in the womb and often fades last, yet we treat it as an afterthought—until something goes wrong.

During the pandemic's height, Yale cell biologist Derek Toomre noticed an urgent gap: COVID-19 was stealing smell before other symptoms emerged. Testing remained expensive, slow, inaccessible. "Loss of smell was happening earlier than fever or cough," he observed. "So why not test for smell itself?"

That question became invention. Collaborating across disciplines, Toomre designed a simple rub-and-sniff card requiring no lab, no swabs, no electricity—only the human nose and a mobile phone. Users rubbed scent panels, identified odors, and logged answers through an app. When many failed the same scents, the system flagged potential outbreaks.

This open-science innovation, U-Smell-It, won the XPRIZE for Rapid COVID Testing in 2021, proving that something as humble as a smell card could stand beside molecular diagnostics. "The real honor," Toomre said, "will come when this test keeps people healthy, schools open, and economies thriving."

Behind this achievement stands Kimmo Piironen, a Finnish multi-entrepreneur who transforms complex technologies into mobile tools. While Toomre brought science, Piironen brought execution—architecture to scale a university experiment into a global sensory platform. "Our goal was to make smell testing something anyone could do, anywhere, anytime."

Together, they built a bridge between laboratory precision and everyday simplicity. The result costs less than dinner for two yet carries implications for neurology, wellness, and data science. Each test becomes a micro-signal in a vast dataset, capturing how human smell shifts across time, geography, and health.

When WTSA encountered U-Smell-It, the alignment felt immediate. We'd long advocated for sensory awareness, studying how loss affects nutrition, mood, and quality of life. Here was a tool that made those ideas tangible. Together, we're offering special-edition cards for screening, education, training, and research.

Each $35 set supports WTSA's nonprofit mission ($5 per purchase). The cards are flat, recyclable, elegantly printed. You rub designated graphics, inhale, and enter answers through the secure app. Within seconds, you receive feedback. Over months or years, patterns emerge for both you and the global scientific community.

Traditional olfactory testing—UPSIT, Sniffin' Sticks—is costly and time-consuming. U-Smell-It democratizes the process, converting smell testing into citizen science, transforming something deeply personal into collective intelligence. Every data point reveals how environment, age, diet, and illness shape humanity's sensory map.

Smell testing has become a social act. People test themselves, their families, their classrooms. Some discover years of reduced smell; others track recovery, noticing improvements no doctor's chart could quantify. Each result carries a human story: a retired teacher's monthly ritual, a pastry chef recognizing vanilla again "like seeing color return to the world."

The longitudinal data makes this different. One test shows today's status. Ten tests reveal personal change. Thousands chart humanity's olfactory shifts across seasons, regions, and health conditions. U-Smell-It's secure portal aggregates anonymous results, revealing recovery trajectories, early cognitive decline signs, even environmental correlations. A global smell map emerges.

Previously, longitudinal olfactory data was limited to small laboratory cohorts. Now, with a fast and easy home test, sample sizes expand exponentially. Each participant becomes a data node, enriching our collective understanding of human perception—citizen science at its most intimate, the body as both sensor and storyteller.

But data must move hearts to matter. Each test becomes a moment of reflection—a pause to notice what's in the air. The ritual of rubbing, smelling, thinking, and logging transforms the invisible into something embodied. Those moments accumulate into longitudinal data for science and longitudinal awareness for the self.

"If you make a test both rigorous and delightful," Piironen notes, "you create engagement. And engagement is the key to meaningful data." He sees U-Smell-It as participatory diagnostics—tools that empower individuals while feeding reliable information to researchers.

Toomre approaches it through neuroscience. "Olfactory neurons are among the few that regenerate throughout life. Changes in smell reveal much about the brain's resilience." His focus now: longitudinal data revealing how smell recovers, how it correlates with age, mood, diet, geography.

That idea—smell as living biomarker—is rippling through the scientific community. Collaborations are forming between olfactory researchers, neurologists, and data scientists. WTSA's research arm is cross-referencing smell-performance data with environmental variables and nutrition studies, building toward predictive models for public health and personalized wellness.

Yet technology alone cannot repair smell's cultural neglect. WTSA integrates these sets into workshops, school programs, and sensory retreats. When children test alongside scientists, hierarchy dissolves: everyone participates in discovery. When elders use them in community centers, they're reminded their sensory experiences matter.

The cards can become conversation starters across disciplines. Chefs can pair them with flavor exercises; perfumers can use them for audience calibration; physicians include them in cognitive assessments. The data lives in the cloud, but impact is tactile, social, immediate.

Science advances not only through instruments but through intimacy. Smelling is breathing in the world. Every inhalation carries molecules that touch the brain directly. To measure that is to measure connection itself. When participants rub a card, they're momentarily researchers and subjects, artists and analysts—adding one pixel to the portrait of human perception.

At WTSA, we see this collaboration as a blueprint: scientists ensure rigor, technologists ensure reach, mission-driven organizations ensure meaning. Proceeds from each set fund new studies, public education, and support for people with sensory disorders.

The future of sensory science will be built through partnerships that respect curiosity and compassion. The longitudinal data we gather could reveal how stress, diet, or environment shape humanity's sensory landscape. But even before algorithms finish their analysis, every participant who takes a moment to notice has accomplished something profound: they've paid attention.

That attention is the quiet revolution Toomre and Piironen set in motion—a shift from passive observation to active awareness. Once you start noticing smell, you notice everything: the world's hidden textures, your own emotional topography, the thread connecting body to environment. In that awareness lies resilience, empathy, perhaps even joy.

Thousands worldwide now hold a U-Smell-It card, testing recovery or satisfying curiosity. Their results flow securely into a growing database capturing not just data but human experience—a global chorus saying, I can smell. I'm paying attention.

Join that chorus. Listen to our conversation with Derek Toomre and Kimmo Piironen on The World of Taste & Smell Podcast. Then experience it yourself: order the U-Smell-It × WTSA Sensory Health Set. Rub, breathe, notice, record. With each card, you contribute to understanding the senses that make us human.