These two experts say they wouldn't recommend them.

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Makers of UV sanitizers claim their products can sterilize anything in minutes. Many say that their sanitizers can kill up to 99.99% of germs on whatever object you put into the device's UV radiation. But do the UV sanitizers actually work? Here's the lowdown.

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First of all, what is UV radiation?

UV stands for ultraviolet, a form of electromagnetic radiation. The most common form of UV radiation is sunlight, which produces the three main types of UV rays: UVA (which is linked to skin aging), UVB (which can cause sunburn), and UVC (which is blocked by the Earth's atmosphere before it can even reach us). It's UVC—the highest-energy UV ray of the three—that's used in UV sanitizers.

UVC radiation is a "known disinfectant for air, water, and nonporous surfaces," according to the US Food and Drug Administration (FDA). In fact, the agency reports that UVC radiation has been used successfully for decades to reduce the spread of bacterial diseases like tuberculosis. Although the viruses they studied are different from the SARS-CoV-2 virus that causes COVID-19, researchers recently published a paper in Scientific Reports showing that UVC radiation can inactivate at least two types of coronavirus. But so far, there's very little data about the wavelength, dose, and duration of UVC radiation that may be effective in inactivating the SARS-CoV-2 virus specifically, according to the FDA.

The Centers for Disease Control and Prevention (CDC) describes high-intensity UV radiation as an "alternative disinfection method." But the CDC also points out that UV lights aren't on List N, a list of all disinfectants reviewed and approved by the Environmental Protection Agency (EPA) to kill the SARS-CoV-2 virus.

How do UV sanitizers work?

UV sanitizers destroy viruses and kill bacteria by using their lights to emit UV rays, targeting proteins and genetic material (DNA and RNA). "They speed up cross-linking of this genetic material, which reduces the ability of the genetic material to participate in healthy replication," Karen Dobos, PhD, professor in the department of microbiology, immunology, and pathology at Colorado State University, tells Health.

UV sanitizers are designed to disinfect a wide range of surfaces, from cell phones to jewelry to stuffed animals. It's important to remember that the sanitizers definitely shouldn't be used on hands (or the skin on any other part of your body, for that matter), William L. Schreiber, PhD, chair of the department of chemistry and physics at Monmouth University in New Jersey, tells Health. The FDA notes that there have been reports of skin and eye burns resulting from improper installation of UVC lamps in rooms accessible to humans.

There are different types of UV sanitizers that are available—from wands to zip-up pouches—to sanitize different types of items. For example, while a wand might be good for targeting household items like doorknobs, a pouch might be best for fitting smaller items like a phone.

Do UV sanitizers actually work?

Again, UV rays have been used as a disinfectant for years. Some hospitals rely on them to help sterilize surfaces, and a large study published in The Lancet found that UVC light used in hospitals cut transmission of four major superbugs by 30%.

But UV sanitizers designed for personal use may not be as powerful. "The energy emitted from these bulbs has to be very low to be sold for personal use, which isn't the case for industrial applications," Dobos says. Because they are lower energy, they are likely less effective against microbes (like bacteria, fungi, and viruses) than industrial UV sanitizers, she points out.

The companies selling these products make bold claims. Typically, these claims are based on lab testing by the company selling the product, but it's important to remember that none of these claims have been confirmed by the EPA. Since germs, viruses, and bacteria are invisible to the naked eye, there's no way of knowing how effective the products are when you use them.

Another point to consider when it comes to personal UV sanitizers is that the energy their lights emit wanes over time. "As it decays, it becomes even less effective for its target, and I don't know how a person could tell how these bulbs are decaying," Dobos says. "I'm sure there's a 'replace by' date, but most of us only replace a light bulb when it goes completely out. This is well beyond the effective time for a UV source."

There's also the fact that using a personal UV sanitizer can actually do more harm than good in the long run. "They can be dangerous, especially with repeated exposure," Dobos warns. She points out that because they replicate and mutate so much faster than other types of organisms, many microbes will naturally have some adaptation or resistance to the UV light. "This population of microbes will get greater and greater within your home, especially with repeated exposure," she explains.

What's the best way to disinfect surfaces?

For all the above reasons, neither Dobos nor Schreiber recommends using UV sanitizers for personal use. Instead, Dobos says cleaning and routine disinfection are the best way to maintain clean, safe surfaces; healthy air ventilation helps, too. "Also, time is on our side," she says. "Most microbes are not stable on dry surfaces—they dry up and die. So keeping surfaces dry, and not constantly using them helps."

The CDC advises using a household cleaner that contains soap or detergent to decrease the risk of infection from surfaces in your home. And when it comes to preventing COVID-19 specifically, the agency notes that disinfection at home is "likely not needed" unless someone in your household is sick, or someone who has tested positive for COVID-19 has been in your home within the last 24 hours. If so, the CDC recommends using a product from EPA's List N to disinfect surfaces and items in your home.

Of course, using a UV sanitizer is a personal choice. If you decide to invest in one, carefully read over the manufacturer's claims and offerings before deciding which device to buy. And don't be fooled by a product that claims to "kill COVID-19." As the EPA points out, COVID-19 itself is a disease, and diseases can't be "killed."

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