UVC, UVA and Visible Light: What’s the Best Disinfection Solution for You?

ultraviolet light


ultraviolet light disinfection


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.


Table of Contents


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:

  • Visible light
  • Ultraviolet A, or UVA
  • Ultraviolet C, or UVC

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.


ultraviolet and visible light spectrum


As you travel left along 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

what is 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:

  • MRSA
  • Staph
  • Strep
  • Noroviruses

It also works on these foodborne pathogens:

  • coli
  • Salmonella
  • Listeria
  • Shigella
  • MRSA

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.

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 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 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 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

what is 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 day cares. 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.


Quick Guide: Which Type of Light Disinfection is Best for You?

The best light 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:

  1. What regulations and best practices do we need to follow? The CDC has guidelines for disinfection and sterilization in health care facilities, for example.
  2. What specific pathogens do we want to protect against? If you operate a food production plant, you’ll want to pay more attention to foodborne pathogens like salmonella and E. coli.
  3. How quickly do we need to kill bacteria and deactivate viruses? UVC light disinfects in seconds, whereas UVA light takes several hours to work on pathogens.
  4. Do we need to deactivate viruses? If yes, don’t choose visible light. UVA light has potential to deactivate  viruses, while UVC light has been proven to do so.
  5. Where can we install the solution? The distance between the light source and a surface impacts its effectiveness.
  6. What are the risks of not eliminating pathogens? In the end, the level of effectiveness you need depends on what you stand to lose.


Next, consider your occupancy patterns with these questions:

  1. What are all the rooms or areas we want to disinfect? Breaking down your needs will help you choose the best solution for each room.
  2. How often and how long are the rooms unoccupied? If a room is frequently unoccupied, UVC light is the quickest and most effective solution.
  3. How long do people spend in each room? While UVA light is safer than UVC light, it’s not a great solution for areas where employees work all day, every day.
  4. Is the room customer-facing or staff-only? Since UVA light produces a slight glow, you may not want to use it in areas with customer traffic.


Common Applications for Light Disinfection

Still not sure what to do? Check out these common use cases for different types of light disinfection.


Hospitals and Clinics

uv light disinfection for hospitals


Visible and UV light disinfection is ideal for hospitals and clinics. Medical facilities need to maintain rigorous cleanliness standards with as little disruption to patients and staff as possible.

Here’s how you can use light disinfection to disinfect different areas of your facility:

  • Waiting areas and nurses’ stations: Install visible light or UVA in rooms where people frequently come and go.
  • Operating rooms: Use visible light to disinfect during an in-progress surgery and UVC once the room is empty.
  • Patient rooms: Use visible light or UVA depending on the length of patient stay. Bring a mobile UVC unit to rooms after each visit.

Check out this resource to learn more about light disinfection solutions for hospitals and clinics.


Food and Beverage Manufacturers

uv light for food sterilization


Foodborne pathogens are a major concern for food and beverage manufacturers. Light disinfection can protect your workers from bringing pathogens in and out of your facility, and it’s a safe, efficient way to sterilize food.

If you operate a food processing plant, here’s an example of how you might use light disinfection:

  • Assembly lines and workstations: Protect workers by using visible light or UVA during shifts and UVC during planned downtime. Use UVC light in a covered portion of the assembly line to sterilize food.
  • Break room: Either visible light or UVA can be a good option, since breaks are short. Then, do a deep disinfection with UVC after hours.
  • Shipping and receiving: Depending on how much time employees spend in loading dock areas, choose visible light or UVA. UVC is best after hours.
  • Storage: Use visible light to avoid degradation of materials over time.

Check out this resource to learn more about light disinfection solutions for food and beverage manufacturers.


Other Business Types


If you’re responsible for cleaning a fitness center, hotel, grocery store, classroom or bus fleet, COVID-19 may have motivated you to seek out light disinfection solutions for the first time.

For these high-traffic businesses, a visible light solution is usually the best option. You can continuously disinfect while people are inside the building using visible light.

Here are potential uses for light disinfection in different types of businesses:

  • Gym facilities: Use visible or indirect UVC light when people are working out. After hours, use a mobile UVC unit to clean equipment.
  • Hospitality: Install visible light sources in high-traffic areas like lobbies and restaurant seating areas. UVA can be used for hallways and fitness centers, and mobile UVC can be used for cleaning empty hotel rooms.
  • Education: Visible light and indirect UVC solutions are safe options when students are in the room. Mobile UVC can be used for deeper disinfection after school.
  • Retail: Choose visible light for disinfecting aisles, carts, check-out lanes and storage areas.
  • Public transportation: Continuously disinfect as people enter and exit with visible light. Use a mobile UVC to disinfect after each shift.

To learn more about light disinfection solutions for these settings, check out this resource.



The best light disinfection solution for you depends on the specific spaces you want to disinfect. Between UVC, UVA and visible light, you can mix and match options to create an environment that’s effective, usable and safe.

In the end, that’s what matters most as you’re evaluating light disinfection solutions: keeping people healthy and safe.


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