Ultraviolet lighting products are under a harsh spotlight, thanks to the coronavirus pandemic. 

As businesses look to reopen in the wake of Covid-19 shutdowns, many are turning to UV light for its ability to destroy germs and other pathogens. But researchers are urging caution over claims made by some UV products now entering the market in this largely unregulated industry. 

Melbourne, Florida-based Healthe, for example, unveiled the Cleanse Portal on April 29. The $20,000 device, which looks like an airport metal detector, is equipped with UV lights meant to deactivate pathogens as people walk through them. In mid-May, the renowned Magnolia Bakery announced it would install the portals at a production facility and two stores in New York City. The same week, Lars Eller of the NHL's Washington Capitals donated a unit to D.C.'s Central Union Mission homeless shelter, an event covered by NHL.com and The Washington Post. At the time, founder Fred Maxik told Inc. Healthe had sold portals to high schools and financial institutions and received interest from a federal agency.

The product's efficacy has been called into question by experts, however, and Healthe recently hit pause. The portal has been removed from the company's website. The units that have already been installed have not yet been activated. Maxik, a former NASA scientist, tells Inc. the company decided to halt sales and submit an Emergency Use Authorization application to the Food and Drug Administration. He says it hasn't been clear whether the FDA, Environmental Protection Agency, or Occupational Safety and Health Administration should be the one to regulate the device. "We want to make sure we don't run afoul of any potential labeling requirements associated with whoever decides to regulate it," he says.

Others in the industry might have influenced the decision to halt distribution. Ed Nardell is a professor of environmental health and infectious diseases at Harvard Medical School and sits on the safety committee for the Illuminating Engineering Society (IES), a 114-year-old organization that bills itself as "the recognized technical and educational authority on illumination." Nardell says the organization relayed concerns about the portal's efficacy to Healthe in recent months.

"The thought of walking through a portal outfitted with UV lamps and having that do anything is absolutely preposterous," says Nardell. "Maybe it will disinfect the back of your hand. It's not easy to get droplets off of complex fibers, so it's certainly not going to get rid of Covid virus in your clothing."

"I think there's truth to that," Maxik says, adding that the company advises rotating within the portal so light can hit from multiple angles. "It's not a perfect technology." Maxik also noted that the portal is meant to be used in conjunction with other cleaning solutions.

Even if the portals are effective, experts differ on whether they're safe. The portals use lower-wavelength far-UVC light pioneered by David Brenner, director of the Center for Radiological Research at Columbia University. Brenner's studies have found that far-UVC light does not cause harm to human eyes, skin, or other tissue. But not everyone is ready to give it the go-ahead.

"We need more research," says Jim Malley, professor of civil and environmental engineering at the University of New Hampshire. "Unless somebody can show us some really clear clinical studies with humans, like we would with a drug or a vaccine, we can't just assume it's safe."

The portal controversy serves as a cautionary tale for business owners seeking technology to help keep their employees and customers healthy. While UV-based disinfecting products have been around for years, more companies have entered the fray in recent months with everything from phone cases to handheld wands. The UV disinfection equipment segment is projected to grow from $2.9 billion in 2020 to $5.3 billion in 2025, according to an April report from research firm Markets and Markets.

It also points to another problem: The UV business remains largely unregulated. "A lot of this industry exists in a regulatory abyss," says Malley.

Even so, experts agree that far-UVC light can be an effective way to disinfect areas when administered properly. Nardell says that UV lights pointed toward ceilings or installed in HVAC systems can help disinfect the air within a space.

Incline Village, Nevada-based HealthySole sells a $5,000 hospital-grade version and a $500 battery-operated version of a UV device for disinfecting the soles of shoes. San Antonio-based Xenex's LightStrike, a $125,000 high-intensity UV light-emitting robot, can disinfect an empty room in minutes. More than 500 hospitals and labs currently use it to help sanitize spaces, with some hospitals reporting that infection rates in patients declined up to 70 percent after the robot was used to clean operating rooms.

As for the UV wands meant to be used on desks, keyboards, and other surfaces: Nardell says the light they emit generally isn't strong enough to have an impact.

"It's the Wild West," he says. "We're in the moment of panic and Covid. It's great to have some new tools, but when you see some of these things, it's just discouraging."