UVC, UVA, and Visible Light, Which is the Best Light Disinfection Solution?
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Expert in LED UV Lighting HVAC/AC
Keeping your customers and employees safe from pathogens has never been a more important priority.
For decades, hospitals and food and beverage manufacturers have used ultraviolet light to disinfect their facilities and products. But starting in 2020, the COVID-19 pandemic sparked a broader interest in eliminating pathogens among all kinds of businesses.
If you’re entering the light disinfection area for the first time, the options available may seem overwhelming.
In this article, we’ll break down the different types of light disinfection available and help you understand which one is best for your facility.
Three Types of Light Disinfection
The type of light you choose determines its disinfection capabilities. When it comes to light disinfection, your main options are:
The visible light spectrum includes light you can see with your eyes. UVA is similar to black light, which causes objects to glow. UVC rays do not penetrate the earth’s atmosphere, so any UVC light you might encounter would be from an artificial light source.
Ultraviolet light has been used for disinfection in the food, health care and water treatment industries for many years. Visible light disinfection, on the other hand, is a relatively new addition in the 21st century, and it works with LED technology.
To understand the differences between UVC, UVA and visible light, it’s helpful to look at a portion of the electromagnetic spectrum.
As you travel left along with the spectrum and wavelength decreases, the effectiveness of light at killing pathogens increases. This means UVC light is the most powerful and fast-acting disinfection.
However, the more effective the light is, the less safe it is for humans. Occupancy, which refers to how often and how long people are in a room, is a way to measure this. While visible light is always safe to be around, direct UVC light is not safe for human occupancy without protective equipment and precautions.
When would you use each type of light? Let’s dive into the different characteristics of UVC, UVA and visible light disinfection.
UVC Light Disinfection
Ultraviolet C, or UVC light, is the most effective option for eliminating pathogens quickly. UVC light has been used for more than 100 years, so it is also the most studied light disinfection solution.
Within about six seconds, a direct UVC light works on the following airborne and surface pathogens:
It also works on these foodborne pathogens:
What about COVID-19? In 2020, Signify worked with the National Emerging Infectious Diseases Laboratories at Boston University and validated that its UVC light sources can inactivate SARS-CoV-2, the virus that causes COVID-19.
The catch is that direct UVC light?is rated for “zero occupancy,” meaning you can’t have anyone in the room when the disinfection occurs. Since UVC is the most powerful type of ultraviolet light, it is not safe to look directly at a UVC lamp or expose skin to UVC light.
As a result, direct UVC light?is best for enclosed spaces that are regularly unoccupied. Operating rooms are a perfect example for when UVC lamps would be beneficial because the rooms are empty for periods of time.
It’s worth noting that most states’ electrical codes require lighting controls to operate UVC technology. Audio and infrared sensors detect when humans are not in the room to prevent accidental exposure.
What is mobile UVC?
Mobile UVC is a large UVC light that can be rolled on wheels and moved easily.
Why would you want a mobile UVC solution? First, UVC light is only effective on surfaces the light reaches. If the light only comes from the ceiling, objects under the table won’t be sanitized. A mobile UVC lamp allows you to disinfect rooms at different angles.
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Another reason is that you can save money with a mobile UVC unit. Because UVC works so quickly, you could use the same unit in multiple rooms rather than installing it everywhere.
Far-UVC vs UVC
Far-UVC is a variation of UVC disinfection that has emerged more recently.
Far-UVC is generally believed to be a safer alternative than UVC, as most research suggests that far-UVC does not penetrate the outer layer of the skin. This means that far-UVC can be used for constant disinfection. However, researchers are not in general consensus on the topic.
A drawback to far-UVC is that the effectiveness is slightly lower than UVC. In addition, while far-UVC offerings are expanding due to demand from the COVID-19 pandemic, it is still more limited compared to more established UVC technology.
Indirect UVC solutions
An emerging UVC technology that allows for continuous occupancy includes wall-mounted and upper air UVC solutions. These devices circulate air through a UVC light to constantly purify the air. This type of solution is ideal for patient rooms, gyms, conference rooms, lobbies and other places where airflow is stagnant.
UVA Light Disinfection
What is uva light disinfection?
Ultraviolet A, or UVA light, is a less powerful but still useful type of ultraviolet light.
UVA light works on many of the same pathogens as UVC light but at a much slower rate. While UVC can kill bacteria almost instantly, UVA light requires several hours. UVA light also has the potential to deactivate viruses.
Importantly, you don’t need to clear the room to use UVA light. A person can safely be under UVA light for eight to 24 hours, depending on the light’s location and intensity.
One drawback to UVA light is that it produces a slight glow on white surfaces, such as teeth and clothing. If you’ve ever played a glow-in-the-dark bowling game, you’ve experienced this effect, as black light emits UVA light.
Also, both UVA and UVC light can break down materials over time?in the same way the sun fades the colors of a lawn chair. For this reason, it’s best to use direct UV light in shorter bursts rather than continuously.
Visible Light Disinfection
The type of visible light used for disinfection is “near ultraviolet,” which is on the violet side of the spectrum.
Visible light allows for continuous occupancy, making it perfect for high-traffic spaces like fitness centers and daycares. It also won’t significantly degrade materials.
You can disinfect bacteria in several hours with visible light, but it has not been shown to work on viruses. If you want, you can use visible light in combination with ultraviolet light. You can turn on visible light when people are around and other disinfection solutions?when your business closes at night.
Which Type of Light Disinfection is Best for You?
The best lighting disinfection solution for your business depends on two things: the level of effectiveness you need and your occupancy patterns.
To determine how effective the light must be at killing pathogens, start by answering these questions:
Next, consider your occupancy patterns with these questions: