For decades, scientists have known about the disinfection ability of UV lights, specifically germicidal UV lights (also known as UV-C lights).
The COVID-19 situation is rapidly changing, and it's causing priorities to shift for a lot of us. Protecting patients, customers, workers, and our families is more important than ever before. Disinfecting frequently used surfaces is also extremely important, and UV light is extremely effective.
Germicidal UV light products tout bacteria kill rates higher than a 99.9% rate. Because of their effectiveness, they're incredibly useful right now for hospitals, medical labs, fire and police stations, and airports, but can also be used in schools, government buildings, office buildings, and hotels.
We'll explain what germicidal UV lights are, how they work, and their advantages for commercial buildings.
What is UVC or germicidal UV light?
Germicidal UV light is a type of light that's best known for its ability to kill bacteria. It's typically used to disinfect rooms and surfaces.
COVID-19 can live on certain surfaces for up to three days, so it's critical to disinfect them at regular intervals.
Although the science behind germicidal UV light has been around for a long time, it hasn't been widely used in the U.S. The CDC and FEMA started to endorse the use in hospitals in the early 2000s. Since then, several medical reviews have noted the effectiveness and the use has jumped in the last 13 years.
Germicidal UV light can include far-UVC light and UVC light, as noted in the chart below.
Germicidal UV light wavelengths
Germicidal UV light, or UVC light, is a particular spectrum of ultraviolet light (UV). UV light occurs naturally from the sunlight or can be generated artificially in light fixtures and bulbs.
You won't be able to see light produced from germicidal UV lights because UV light does not produce visible light.
UV wavelengths can range anywhere from 10 nanometers (nm) to 400 nanometers (nm).
UVC light (germicidal UV light) falls between 200 to 280 nm.
UV-B and UV-A light can also kill bacteria and germs, but exposure can be dangerous and should only be used in certain applications. UV-A light can only kill certain types of bacteria, so it is ineffective against viruses like COVID-19.
How do UVC lights kill bacteria?
Germicidal UV lights can actually change the DNA and RNA of bacteria and viruses, destroying their ability to reproduce.
Bacteria may be resistant to other things like antibiotics, but cannot build up a resistance to UV light.
If you're interested in a more scientific definition, check out this explanation from one of our manufacturers.
The big question right now: Can UV lights kill COVID-19?
Bacteria can be ranked based on their tolerance to disinfectants, like UV lights. Coronaviruses fall into the category of "enveloped viruses," or a Class 3. Class 3 viruses are the easiest to kill. Products that are able to kill more resilient viruses like small and large non-enveloped viruses (Class 1 & 2 viruses) should also be able to kill enveloped viruses like coronaviruses.
Based on this information, UV lights are believed to be highly effective at killing COVID-19. Since the virus is so new, official testing against the novel coronavirus should be underway soon.
It's also important to note UV light does not replace other cleaning measures like washing hands or removing dirt and dust from surfaces. Those are still important actions to take to prevent the spread of COVID-19 and other germs.
Is germicidal UV light safe?
Artificial UV light, just like overexposure to the sun, is known to cause side effects for humans like skin cancer and cataracts.
For safety reasons, most UV products run when there is no one in the room.
However, there are studies that show certain wavelengths of UV light may be safer than others while still killing bacteria.
For example, one study in particular focuses on the use of far-UVC light. That's between the wavelengths of 207 and 222 nm.
Far-UVC is believed to be just as effective at killing germs as higher ranges of UV-C light, but less harmful to our skin and eyes because the light cannot penetrate human skin.
Other studies suggest that wavelengths as low as 185 nm can still germs.
UV light can also be harmful if it's used in the wrong application or in the wrong fixture.
Here's the bottom line when you're selecting germicidal UV light products: Make sure you buy the right light bulb for the right fixture and follow product use guidelines.
Advantages of germicidal UV light
Germicidal UV lights are extremely effective and have several major advantages.
- Pathogen kill rate – Tests show that germicidal UV lights kill up to 99.9% of bacteria and viruses. On top of that, pathogens cannot become resistant to UV light like they can certain antibiotics and antibacterial products.
- Limited chemical exposure – UVC lights work in place of potentially harmful chemicals. It's safe to enter a room after germicidal UV lights are at work, but it might be hard to breath in a room that has just been sprayed down with chemicals.
- Lighting configurations – There are multiple lighting configurations for germicidal UV light, including mobile fixtures. Mobile units are a great option for hospitals, airports, fire and police stations, and the hospitality industry because they're easy to move from room to room. Plus, mobile units are a budget-friendly option compared to installing fixtures in every room.
Can germicidal UV light deteriorate materials or surfaces?
UV light is known to damage materials – that’s why a toddler’s plastic toys left outside over the summer causes the colors to fade and the plastic to be more brittle.
Similarly, broad spectrum UV lights can damage materials. The critical difference to look for is whether the UV light is constantly on or gives short bursts or pulses of disinfecting UV rays.
The germicidal UV light fixtures made by Puro are a good example of a disinfecting light fixture that gives periodic bursts of UVC light to disinfect surfaces with minimal impact on the materials in the space.
Germicidal UV light products
Most germicidal light bulbs are fluorescent bulbs but there are also some low-pressure mercury vapor bulbs and xenon lamps.
We have several types of replacement bulbs available on our site.
If you're looking to install UV products, we also have a line of fixtures available, pictured below. The first two are ceiling fixtures. The one on the far right is a mobile unit.
Covers 100 sq. ft.
Starting at $3,700
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Covers 225 sq. ft.
Starting at $7,099
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Mobile disinfecting unit.
Starting at $8,500
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One important note: UVC light bulbs should only be used in the appropriate light fixtures.
If you have any questions about germicidal UV lights, where to use them, or how they could work for your commercial building, please do not hesitate to contact us.