Tess Eidem and her team at the University of Colorado Boulder fill the lab’s air with tiny particles of cat dander, dust mites, mold, and pollen. These airborne allergens, released into a sealed chamber for testing, are the same ones that trigger sneezing, coughing, and asthma attacks in millions of people.

But what if light could disarm them?

In a new study published in ACS ES&T Air, Eidem and her colleagues have shown that a specific wavelength of ultraviolet light—one considered safe for human exposure—can rapidly reduce the potency of common airborne allergens. Not by killing them (allergens, after all, aren’t alive), but by subtly wrecking their shape so the immune system no longer recognizes them.

“We have found that we can use a passive, generally safe ultraviolet light treatment to quickly inactivate airborne allergens,” said Eidem, a senior research associate in the Department of Civil, Environmental and Architectural Engineering at CU Boulder.

This kind of intervention, she hopes, could someday help ease the burden of allergies and asthma—two conditions that affect over 100 million Americans and cost the U.S. economy tens of billions annually.

Allergens That Linger

If you sneeze around a cat, it’s not the cat that’s triggering your immune system. It’s a protein called Fel d 1, found in cat saliva and skin flakes. The same goes for dogs (Can f 1), mold spores (Asp f 1), and plant pollen like Timothy grass (Phl p 5) and birch (Bet v 1). These proteins can linger in the air for weeks—or even years—long after the original source is gone.

The immune system recognizes the proteins’ specific three-dimensional shapes, triggering an allergic response when antibodies bind to them. That binding process is at the heart of the sneezing, swelling, and wheezing that allergy sufferers know all too well.

But what if those proteins were structurally scrambled? What if they were still floating around—but no longer looked like threats?

That was the radical idea behind this study.

Allergen Origami

The researchers used a particular kind of ultraviolet light called UV222. Unlike the more familiar germicidal UV254 used to sterilize hospitals and labs—too harsh for humans—UV222 is gentler. It doesn’t penetrate deep into skin or eyes, and prior studies have shown it can inactivate airborne viruses without harming people.

In a custom-built, 10-cubic-meter chamber, Eidem and her team aerosolized seven common allergens using a specialized nebulizer. They then bathed the chamber in UV222 light and measured what happened to the allergens over time using a high-sensitivity immunoassay.

The result? A kind of molecular unmasking.

“If your immune system is used to a swan and you unfold the protein so it no longer looks like a swan, you won’t mount an allergic response,” said Eidem.

Rapid Reductions in the Air

After just 30 minutes of exposure to UV222, airborne allergen levels dropped by 20% to 25% on average, depending on the type. In one case, Fel d 1 levels dropped by 61% after 40 minutes, when the protein was exposed without stabilizers that might shield it from damage.

These changes were due to the UV light folding the allergenic proteins, scrambling their surface so antibodies no longer bind to them. The immune system, in effect, no longer sees a threat.

The reductions occurred at UV exposure levels far below the safety thresholds for skin and eye exposure set by the American Conference of Governmental Industrial Hygienists. That makes UV222 a practical candidate for real-world use.

Beyond the Filter

Current allergen control strategies are anything but simple. Removing carpets, washing bedding in hot water, vacuuming every week, bathing pets, and using HEPA filters can help. But they are time-consuming and hard to maintain.

In one 2003 study, researchers asked cat owners to follow such a strict cleaning regime. Of the 219 people enrolled, only 31 completed the full eight-month protocol.

UV222, by contrast, could offer a simpler option.

“Those are pretty rapid reductions when you compare them to months and months of cleaning, ripping up carpet, and bathing your cat,” said Eidem.

Portable versions of the light, she suggested, might someday be used in homes, schools, hospitals, or even dusty basements. People could switch them on in minutes and make a noticeable dent in allergen levels in the air they breathe.

The researchers also suggest potential industrial applications. For instance, for grow houses, animal labs, or food processing facilities where airborne allergens pose risks not only of discomfort but real danger.

What’s Next?

The research raises big questions. Can UV222 meaningfully reduce symptoms in people with severe allergies? Could it help prevent asthma attacks? What happens to the altered proteins after exposure—do they settle, degrade, or stay suspended in the air? Is long-term UV222 exposure harmless?

The team hasn’t answered all of these yet. But they are clear on one thing: the immune system’s inability to recognize these “unfolded” proteins means there’s a real shot at reducing symptoms—if not curing allergies, then at least disarming them.

Over 3,600 Americans died from asthma in 2022. Globally, the disease contributes to about 1,000 deaths every day. Behind those numbers are often tiny, unseen particles; proteins, drifting in the air like invisible triggers.

But maybe now, with just a flick of ultraviolet light, we’ve found a way to switch them off.