Do at-home UV sterilizers really work?
With the holiday season comes an arsenal of gimmicky products that tend to lean more to the fun side than functional. In the pandemic era, this had led to an influx of phone holders and handheld wands that claim to sterilize phones, wallets and even groceries with UV light. But do they work?
Specific wavelengths of light can damage nucleic acids or protein and are effective in killing certain viruses and bacteria. However, these lights have to be fairly concentrated to kill pathogens, which is both difficult and expensive to create in smaller home devices.
Humans are also susceptible to UV damage and lights that are strong enough to kill viruses can cause burns, eye damage and skin cancer. Health Canada recently released an alert warning consumers about UV lights and wands for home use, stating it “has not yet received any evidence to demonstrate that UV lights can protect specifically against COVID-19.”
The public health body also noted there is currently no proof that UV lights are effective against COVID-19 and “should not be used as a substitute for prevention measures such as frequent hand washing, physical distancing, mask-wearing and cleaning and disinfecting”
UV lights also need to be of strong enough to kill pathogens. If the device doesn't have enough power, if the bulb is starting to burn out or if the device isn't focused on the area for a long enough period of time, it won't be effective.
In the UV spectrum, UVA is the longest wavelengths, from 320 to 400 nanometres (nm), and is known to cause some cell damage and indirect DNA damage. This cell damage can cause wrinkles and sunspots and may have an indirect effect on developing some forms of skin cancer. UVB is more intense, and can cause burns, eye damage and can also damage protein and DNA in cells. UVB radiation from the sun is what causes sunburns.
UVC, also known as germicidal UV (200 to 280 nm), is even more potent and can severely damage proteins and DNA in cells. If a human is exposed to concentrated UVC light for even a few seconds, they can come away with burns and eye damage.