Lifx’s bacteria-killing smart lamp works, but here are the small print

Lifx Clean is a new smart lamp with an intriguing touch. Not only is it a fully functional color changing lamp, the company also claims that it is capable of disinfecting surfaces and the air around it. First announced last August, the $ 69.99 Lifx Clean is now being shipped to pre-order customers in the United States, with wide availability planned for this spring.

Lifx has a series of scientific studies, as well as its own laboratory tests to support its claim that Clean is “the world’s first intelligent antibacterial and germicidal light”. But can the lamp work just as well in an ordinary home as it does in the laboratory?

It is no accident that Lifx announced the lamp in a year when we all had to pay more attention than ever to keep ourselves and our homes clean. Lifx CEO David McLauchlan says the company started having initial discussions about developing a product like Lifx Clean last March, in the same month that COVID-19 was officially declared a pandemic by the World Health Organization.

“We saw that the alcohol companies were making hand sanitizers and the clothing companies were making face masks, and I told the team that we can’t do these things, but we make lights,” said McLauchlan by phone. “There is this technology out there, why don’t we investigate and find out if we can do that?”

The “technology” that McLauchlan refers to here is a very specific type of blue light with a wavelength of about 405 nm. This high-energy visible light (HEV) has been shown through a series of studies to “inactivate” (read: kill) a variety of bacteria, including salmonella, E. coli and methicillin-resistant staphylococcus aureus (also known as MRSA ) laboratory based studies.

Other experiments have used it in real-world situations, such as hospitals. In three studies conducted between 2010 and 2013, the researchers found that the lights reduced the number of bacteria on surfaces that were frequently touched in a burn unit in a hospital. The reduction varied widely – between 27 and 90 percent – even within these individual studies, depending on factors such as how many days the light was used and how much activity there was in the room where it was used.

Lifx Clean incorporates this technology into a home lamp by means of a set of eight 405 nm LED lamps, which are next to the standard red, green and blue diodes that you find in other Lifx lamps. The matrix then has a typical diffuser placed over it, which means that it looks almost identical to a standard Lifx lamp.

Its appearance is benign – very different from another light cleaning technology that became popular during the pandemic era: ultraviolet light. Pilot programs used ultraviolet light to clean subways, buses and aircraft cabins, and Transport for London implemented it to disinfect escalator handrails.

UV has fast action, but it is also incredibly dangerous when used incorrectly. This is according to Jim Malley, professor of civil and environmental engineering at the University of New Hampshire, who has been studying the use of ultraviolet rays and other types of light as a disinfectant for more than 30 years. It can cause erythema, the redness of the skin that is most commonly associated with sunburn, and repeated exposure may even be associated with skin cancer, he says. Light is particularly damaging to your eye’s cornea, and exposure to it can cause “the worst headache you have ever imagined”. Although his cornea can usually recover from exposure to ultraviolet rays, Malley told me, repeated damage “appears to be related to early blindness”.

In comparison, HEV light does not have the same problems. “Blue light, 405 nm, doesn’t have that kind of energy,” explains Malley.

The HEV lamp has its own disadvantages. Most notably, the effect of light on bacteria has simply not been studied as much as ultraviolet rays. Much of the research that has been done has focused mainly on its ability to kill bacteria, and there is less evidence to suggest that it is effective against viruses. This is a very important warning, as COVID-19 is caused by the coronavirus SARS-CoV-2 – a virus.

Lifx is not ashamed to point this out. In its announcement for Lifx Clean last August, the company explicitly said that “no claims are currently being made that the product is effective in an antiviral capability of any kind, including SARS-CoV-2”.

“I really want to be emphatic that we are not trying to sell you as a ‘coronavirus killer’,” warns McLauchlan.

But Lifx still believes that a disinfectant lamp, even if it is antibacterial rather than antiviral, can help in an era of global viral pandemic. After all, bacterial infections can create serious complications for anyone infected with a virus.

HEV lights are not particularly fast when they are being used to kill bacteria. A 2009 study found that it took 60 and 90 minutes for the 405 nm light to inactivate almost all of the bacteria under test, despite the fact that the light was positioned a total of 2 cm away from it. Hospital studies focused on the continuous use of light during the day, from eight to 14 hours or more to achieve the desired bacterial reductions. In comparison, ultraviolet light can kill many bacteria and viruses in seconds.

These disadvantages mean that HEV lamps have not become popular as a disinfection technology, despite the research that proves it, Malley told me.

“It is not competitive, it is not practical. You just can’t have hours and hours of contact time, ”says Malley. In a world where an ultraviolet light can sanitize a phone in 60 seconds, the 405 nm light “cannot compete”.

Lifx provided a report for The Verge of their light tests against E. coli and MRSA, which showed how their light behaved in periods ranging from two to 12 hours, over a variety of distances. While Lifx Clean can kill more than 80 percent of E. coli bacteria on a glass surface in two hours under the right conditions, you’d have to run Lifx’s Clean bulb for up to eight hours to achieve a similar death rate for MRSA.

The time involved in killing bacteria is a disadvantage, but McLauchlan argues that the smart lamp’s programming features mean that you can activate it automatically when you’re not around. “You can literally turn on your lights at midnight when everyone is in bed and stay in disinfectant mode until 6 am and provide a disinfectant effect on that room or surface,” says McLauchlan.

The effectiveness of light also decreases the further you are from a given surface. The above results were achieved with the lamp just 40 cm away from the bacteria, which places it approximately at the height of the table lamp. Move the bulb further away, and it usually takes longer to kill the same amount of bacteria. Even after eight hours, Lifx tests show that the bulb killed only about half of the MRSA bacteria on a surface three feet away, or just over 65% of E. coli.

These results mean that you are unlikely to see much impact if you intend to use Lifx Clean as a suspended light. Instead, the company sees people using the lamp in fixtures above tables and other surfaces. To your credit, Lifx is being honest about these limitations, and the test results are publicly available on its website for everyone to see. If you are planning to take one of the lamps, it is worth taking a reading to understand where and for how long you will need to leave the lamp working for an effect.

But there are other disadvantages to using HEV light that no amount of intelligent programming or intelligent positioning will be able to overcome. Lifx, for example, initially said that Lifx Clean would be able to disinfect the air around the lamp. However, the slow disinfection time makes this a very difficult feat, Malley explains, because of how the air particles tend to move.

“They won’t be able to keep the blue light in that air particle long enough,” says Malley. If the bacterium is really close to blue light, then you might see a reduction, he speculates, “but in general, I don’t think it can compete because you just can’t keep the air close to that death zone long enough.”

There are all kinds of variations in people’s homes that can affect how safely the bulb kills bacteria. Disinfecting light is, by its very nature, a line of sight technology, so any areas of shadow will not be disinfected and any lamps on the way will also impair its effectiveness. One of the 2013 hospital studies found that the light killed an average of 15 percent less bacteria on the side of a room that was indirectly lit compared to the areas directly under the ceiling lights. Nor can it penetrate deeply into porous surfaces, admits McLauchlan.

The amount of variation in the average of a home may mean that the results cited by Lifx from its laboratory tests will not correspond exactly to the real world. For reference, all the test results mentioned above had the bacteria sitting on a glass slide. This may work for non-porous surfaces, such as kitchen or bathroom countertops, but Malley warns that trying to generalize too much from laboratory results like this to an ordinary home can end up looking “very unreal”.

Variations like this between laboratory results and how people actually use the products at home are nothing new, says John Coia, clinical microbiologist and professor of clinical microbiology at the University of Southern Denmark. Coia has co-authored several real-world studies that found that HEV light can reduce the amount of bacteria when used in hospitals. He points out that even when it comes to traditional chemical disinfectant, many people may no longer be using the correct concentrations.

“Can you argue that people are using the right concentration [of HEV light], but do people use disinfectants in the right concentration? The answer is probably not, ”says Coia. “In many cases, they probably use concentrations that are really sublethal.”

Everyone we spoke to, as well as Lifx, agreed that Lifx Clean will not replace any normal cleaning. But used properly, it can be an extra tool in your cleaning arsenal. “I would not see [HEV light] as a substitute for cleaning, but as an adjunct ”, says Coia.

Several studies have shown that, under the right circumstances, HEV lamps like Lifx Clean can certainly kill bacteria. But even Lifx’s own laboratory tests showed the limitations of the technology. It needs enough time, it needs to be at the right distance and it needs a direct line of sight for the bacteria in order to kill it. Lifx’s “germicidal smart light” is not snake oil, but neither is it a silver bullet that will save you from your weekly cleaning tasks.