Ultraviolet (UV) light is a type of radiation. It has more energy than radio waves or visible light but less energy than X-rays or gamma rays.
You can be exposed to UV light via natural sunlight or through human-made sources like tanning beds.
UV light has been used as a means to kill germs like bacteria and viruses. You may have also heard of its use for killing SARS-CoV-2, the new coronavirus that causes COVID-19.
In this article, we’ll explore how UV light is used to kill germs, how effective it is at eliminating the new coronavirus, and more.
There are several types of UV light. They’re classified according to how much energy they have.
Types of UV light
- UVA light has the lowest amount of energy. When you’re out in the sun, you’re mainly being exposed to UVA light. Exposure to UVA light has been linked to skin aging and damage.
- UVB light sits in the middle of the UV light spectrum. A small portion of sunlight contains UVB light. It’s the main type of UV light that contributes to sunburns and causes most skin cancers.
- UVC light has the most energy. UVC light from the sun is mostly absorbed in the Earth’s ozone, so you’re not normally exposed to it on a daily basis. However, there are various human-made sources of UVC light.
UVC light is the type of UV light that’s most effective at killing germs. It can be used to disinfect surfaces, air, and liquids.
UVC light kills germs like viruses and bacteria through damaging molecules like nucleic acids and proteins. This makes the germ incapable of performing the processes that it needs to survive.
UVC light can be used to kill the new coronavirus, SARS-CoV-2. Let’s look at what the research has discovered about UVC light and this coronavirus so far.
UVC light for disinfecting liquids
A recent study in the American Journal of Infection Control (AJIC) investigated using UVC light to kill large amounts of the new coronavirus in liquid cultures.
The study found that UVC light exposure completely inactivated the virus in 9 minutes.
UVC light for disinfecting surfaces
Another study, also published in the AJIC, looked at using a specific type of UVC light to kill SARS-CoV-2 on laboratory surfaces. The study found that the UVC light reduced the live coronavirus by 99.7 percent in 30 seconds.
The type of UVC light used in this study is called far-UVC light, which is UVC light between the wavelengths of 207 and 222 nanometersTrusted Source.
Far-UVC light is still damaging to germs but is less of a hazard to your skin and eyes than other types of UVC light.
UVC light for disinfecting air
One studyTrusted Source, published in the journal Scientific Reports, explored using far-UVC light to kill two types of human coronaviruses in the air. These two coronaviruses, 229E and OC43, can cause the common cold in humans.
Based off their results with these viruses, researchers estimated that, when applied to current regulatory standards, far-UVC light could kill 99.9 percent of airborne coronaviruses in about 25 minutes. They believe that these findings would extend to SARS-CoV-2 as well.
Because it can effectively inactivate the new coronavirus without using chemicals, UVC light is an attractive option for disinfection. Special lamps that emit UVC light are typically used for this purpose.
Currently, the use of UVC light for disinfection is mostly limited to healthcare settings to disinfect things like:
- operating rooms
- personal protective equipment (PPE), such as N95 face masks
One of the downsides to UVC light is that it needs direct contact to be helpful. That means that if an area is in shadow or covered by dust, UVC light will be less effective at killing germs that may be present.
While UVC light can quickly kill SARS-CoV-2, the Food and Drug Administration (FDA)Trusted Source notes some additional risks for using it at home:
- The optimal length of exposure, wavelength, and dose of UVC light for killing SARS-CoV-2 is yet to be determined.
- Exposure to some types of UVC light can damage your skin or eyes.
- The types of UVC light lamps sold for at-home use are often lower in intensity. That means it may take a longer time to kill germs.
- UVC light lamps can potentially contain mercury or produce ozone, both of which can be harmful to humans.
- It’s possible that prolonged exposure to UVC light can cause materials like textiles, plastics, or polymers to degrade.
Far-UVC light may be a potentially safer option for disinfection. ResearchTrusted Source has indicated that, unlike other types of UVC light, it doesn’t appear to penetrate the outer layers of the skin or eye. However, further safety studies are needed.
Innovation in disinfection
Various companies are developing innovative technologies for UVC light disinfection. These focus on automation of the disinfection process using robots.
One example is the LightStrike robotTrusted Source, which can kill 99.99 percent of SARS-CoV-2 viral particles in 2 minutes. In the future, it’s possible that robots like this could be used for disinfection of hospital rooms, hotel rooms, and airplanes.
You may have heard about some methods to kill the new coronavirus using UV light or high temperatures.
Let’s take a closer look at some popular myths and why they could be potentially dangerous, as well as the safest known ways to prevent COVID-19.
Myth #1: Sun exposure can protect you from COVID-19
While sunlight does contain UV light, it’s mostly UVA and UVB light. These types of UV light are less effective at killing SARS-CoV-2.
Perhaps more importantly, prolonged exposure can also lead to skin damage, sunburn, or even skin cancer.
Myth #2: Using a UV lamp on your body can protect you from COVID-19
While a UV lamp may be used to disinfect surfaces, avoid using one to kill the new coronavirus on your hands or other parts of your body.
Remember, most types of UV light can be harmful to people. Exposure can result in skin irritation, damage, or burns.
Myth #3: Sitting in a hot bath can prevent COVID-19
This method won’t prevent you from becoming ill with COVID-19. In fact, your body temperature will remain pretty much the same in a hot bath.
Additionally, sitting in a very hot bath can actually harm you by causing burning or scalding.
Myth #4: The hot air from a hand dryer can kill the virus on your hands
While the air emitted from a hand dryer is warm, it won’t kill SARS-CoV-2 on your hands.
Fact: There are several safe ways to prevent getting COVID-19
To prevent becoming ill with COVID-19, take the following steps:
- Try to stay home as much as possible. If you must go out, practice physical distancing (maintaining 6 feet of distance from others), wear a face covering, and avoid large gatherings.
- Wash your hands frequently using soap and warm water or use an alcohol-based hand sanitizer. Avoid touching your face, nose, or mouth if your hands aren’t clean.
- Regularly disinfect high-touch surfaces in your home, such as doorknobs, appliance handles, and countertops. The Environmental Protection Agency (EPA) has a list of products that are effective at killing SARS-CoV-2.
- Avoid being around people who are sick. Similarly, stay home if you’re ill.
The type of UV light that’s most effective at killing germs, like viruses and bacteria, is UVC light.
UVC light can effectively kill SARS-CoV-2, the new coronavirus that causes COVID-19. Much of the research on this topic focuses on far-UVC light. This is a type of UVC light that still kills germs but is less harmful to humans.
UVC light is mainly used for disinfection in healthcare settings. While you can buy a UVC light lamp for your home, remember that these lamps are often lower in intensity.
Also, the optimal length of exposure, wavelength, and dose of UVC light needed for killing the new coronavirus is yet to be determined.