Step into the Light (Carefully): A UVC Systems Buyers Guide

By Tristan Williams, Finsen Tech Group

Environmental disinfection has become the new battleground in the ongoing fight to reduce the risk of infection transmission. Evidence demonstrating the persistent contamination of environmental surfaces, despite traditional cleaning and disinfection methods, has led to a widespread acceptance that there is a demonstrative need for using supplementary disinfection technologies.

Ultraviolet C (UVC) disinfection is one type of no-touch technology proven to be a successful adjunct to manual cleaning in reducing environmental bioburden. The unprecedented COVID-19 pandemic and the recognized efficacy of UVC against this virus has greatly accelerated the growth of the UVC disinfection market.

Unsurprisingly, this has resulted in a surge in “new” UVC systems being offered for consumer purchase. This article provides some examples and offers a genuine buyers guide.

Power is Everything

UVC is a disinfection technology that is entirely based on light (admittedly, at a specific wavelength). As such, it is rightly and unavoidably governed by the laws of physics whereby, just like a soundwave reducing in volume the greater the distance from the source, the same thing happens with UVC light.

There is a reduction in UVC intensity over distance and, therefore, the more UVC power the system has to begin with, the more effective the system will be over distance. For this reason, it is critical to know, understand and ask any potential UVC supplier to specify the exact UVC output of the system being considered for purchase, expressed as UVC watts.

In the example in Image 1, a UVC manufacturer is claiming to have 2,000 watts of UVC energy. This is untrue as UVC is generated as a percentage of electrical input (i.e., it takes power to create). Remember:

  • Amount of UVC light generated is critical for dose calculations.
  • Electrical consumption is quoted above (2,000 watts), not UVC output. This is misleading.
  • Claims such as this will (and have) trickle down to tender specifications.

BUYERS TIP #1: Many UVC suppliers will provide their electrical consumption in watts rather than the UVC output. Ask for clarification or the datasheet on the bulb/LED/emitter (a reputable OEM will have these on file) prior to purchase.

Log Reduction (On What?)

Table 1. Illustration of log reduction

Log reduction is a mathematical term used to express the relative number of living microbes eliminated by a disinfectant and corresponds to inactivating 90% of a target microbe, with the count being reduced by a factor of 10. Table 1 illustrates this. A simple way to remember what log reduction means is to simply “count the nines” (i.e., 90% has one nine and is one log, 99% has two nines and is two log and so on).

However, it is critical to point out that different organisms require different amounts of UVC to destroy. So, when manufacturers make a claim of “kills 99.9999%” (see Image 2), the question to ask is “99.9999% of what?”

Image 2. Manufacturers’ claims regarding effectiveness

If the manufacturer is testing on an organism that requires only a relatively low dose (COVID-19 for example), then their product will achieve a higher log reduction than if used with a harder to kill organism (e.g., MRSA). Furthermore, if the claim is made without reference to an organism, then it is almost meaningless (see Image 2).

BUYERS TIP #2: Ask for details – the burden of proof lies with the manufacturer. Ask for details as to which organism the log reduction claims refer to – is it relevant to the application? Ask for details as to which material it was tested on.

It’s About Time

UVC dosage is a relatively straightforward calculation, and it is entirely based upon duration or, more simply, time. While all manufacturers acknowledge that time is important as this affects availability of rooms and areas that need to be disinfected with UVC, the time needed to disinfect is directly related to the power (amount of UVC) that the system can produce.

Image 3. Manufacturer’s claim about disinfection time

Faster is not necessarily better as to perform only a partial disinfection in order to reduce the cycle time means only a certain number (or a certain type) of organism will be destroyed. For example, the manufacturer in Image 3 is using cycle time as one of its key benefits but, simple math says the UVC energy it produces does not allow for a full disinfection within this timeframe.

BUYERS TIP #3: How accurate is the time calculation? What methodology was used: Timer? Room scanning? Reflective dose? What are the tolerances for error
(both machine and human)? When is the time calculated? At what point is the time calculated: Before the cycle? During the cycle? Why is the time calculation better than other systems? Where is the time calculated: In the room? Outside the room? From a book/table or based on real-time room data? What organism will be
provided a terminal dose: MRSA? C-Diff?

Safety First

UVC is a low-risk light source; however, no personnel should be in the room for room disinfection at any point during the treatment. As such, it is highly recommended to check that the systems being considered feature an active safety system that ensures the system is safe to use. The system must have been exhaustively tested and rigorously designed, and the following features should be included:

Emergency Stop: There should be at least one easy-to-access emergency stop button mounted on the handle at waist height. These must have full authority over the entire system and, if used, will cause immediate shutdown, but also prevent further operation of any system.

Stable Structure: The base should be supportive enough to ensure there is no risk of toppling, and it should be able to traverse elevator thresholds and small cables easily. The castors ideally should feature both a directional and motion brake, ensuring that the system stays where it needs to stay.

Motion Detection: The most important feature that must be integrated is a passive infrared sensor (PIR) for heat and motion. Ideally, these should be built into the handle at waist height (to ensure clearance against beds and furniture), and these sensors must have full digital authority over the entire system in the event of an intrusion. Any movement when the system is operating will result in an instant shutdown (as well as the system not letting a cycle begin if the room is not still for a set period).

BUYERS TIP #4: Safety is paramount above all other requirements. Ask for details on active safety systems, how they work, response times, sensitivity, range and effectiveness.

Adapt and Evolve

The ability to adapt to future needs is one of the most straightforward, and often overlooked, aspects of UVC disinfection systems, but it is critical if users are going to extract maximum value from the machine. It also is important to consider not just where the system will be used now, but where needs may arise in the future. Key specifications to review include the following:

Size: Simply, will it fit where the user wants to put it. Ask for dimensions, weight, etc. – but the most overlooked criteria is height. Many systems are very tall, and this can cause difficulties when using the system (door access, low ceilings, etc.), but also when transporting (fitting in a vehicle, pushing along a corridor – can users see over the top?). These are simple checks but can make an enormous difference. A useful yardstick is to check the size of the machine against the footprint of a wheelchair as that will allow uses to take advantage of existing accessibility pathways.

Power: 220v or 110v – which is needed? Check that the system will function on the voltage that is need for the location. Due to the use of both voltages across the globe, some systems automatically will function on both, but always ask. The last thing anyone needs is to have a system arrive that can’t be used!

BUYERS TIP #5: Make sure the machine can adapt to changing needs rather than requiring the user to adapt to the machine’s needs. The more adaptable the system is, the more areas it will be able to disinfect.

Service and Support

Service is everything. No matter whether the product is very expensive or very cheap, at some point users will need to reach out for after-sales support and service. This could be in the form of training or technical support, or it could be in a full-fledged breakdown scenario. Remember, when users choose a product, they are partnering with the company’s service division for a long period. Making the right choice is key to a seamless integration of UVC disinfection into any workflow.

BUYERS TIP #6: It is vital to consider the service aspect as much as the performance and cost of the system itself.

Proof for the Purchase

When a UVC disinfection system is being evaluated for purchase, the purchase is designated for use in a specific area or for a specific object. For that reason, it is fundamental to ensure that the products being evaluated have product-specific supporting data.

Why product specific? There are an enormous number of variables in UVC disinfection systems: reflector performance, type of tube, power, dosage calculation, etc. – all of these have a profound effect upon the effectiveness of the product to meet the application’s needs and provide terminal disinfection.

The data provided should be

  • Product specific, not a generic referral to similar products data.
  • Relevant, on a microorganism similar to one which needs to be eradicated and in a similar environment.
  • Published on a recognized site.
  • Peer reviewed by key opinion leaders within the industry.
  • Concise and clear, with objectives outlined at the start and results clearly defined.
  • Using recognized methodology, with test protocols that are a standard industry practice.

BUYERS TIP #7: This is the ultimate question: Will the system do what it needs to, when it needs to do it? Ask for clarification, check for validation and don’t be afraid to push for answers.

Tristan Williams is the chief technical officer for the Finsen Tech Group. Originally from a background in high reliability engineering, Williams transitioned into working in the UVC sector, leading the Tech Ops and R&D teams for the Finsen Tech Group for the past four years. He is a passionate advocate of the critical role that technology can play in reducing the risks of infection and the importance of self-regulation for emerging technologies. For further information, visit or email