Environmental disinfection has emerged as a new front in the struggle to limit the risk of infection transmission. Data revealing chronic contamination of environmental surfaces despite typical cleaning and disinfection methods has led to universal recognition that further disinfection technologies are required.

UVC light disinfection is a type of non-touch technology that has proven to be a successful adjunct to manual cleaning in reducing the ecological burden. The unprecedented event of the COVID-19 pandemic and the recognized effectiveness of UVC against this virus has greatly accelerated the growth of the UVC disinfection market. Not surprisingly, this has led to an increase in “new” UVC systems being made available to consumers.

With UVC light, it’s all about power – disinfection becomes real

UVC is a disinfection technology that relies entirely on light (of course at a certain wavelength). As such, it is inherently governed by physical rules, such as how the volume of a sound wave diminishes with increasing distance from its source, so does UVC light.

Because UVC intensity decreases with distance, the more UVC power you start with, the more effective the system will be over distance. As a result, it is critical that you understand and ask any possible UVC supplier you are considering for a purchase what the system irradiance is in micro watts/cm2 at a distance of one meter. UVC light is produced as a percentage of the electrical energy input (ie it takes energy to create).

Advice for clients

Many UVC equipment suppliers will display power consumption in watts rather than irradiance. Ask for clarification or the UVC source’s datasheet before purchasing (a reputable manufacturer will have these on file).

Log reduction (on what?)

Log reduction is a mathematical term used to express the relative number of live microbes removed by a disinfectant and corresponds to 90% inactivation of a target microbe, with the number reduced by a factor of 10. The table below illustrates this:

A simple way to remember what it means is to simply “count the nine digits” (ie 90% has a new “9” and is a 1-log reduction, 99% has two “nine” digits and is a 2 -log and so on).

However, it is important to point out that different organisms require different amounts of UVC light to be destroyed. So when manufacturers claim it “kills 99.9999%”, the question to ask is “99.9999% of what?”

If the manufacturer is testing on an organism that only requires a relatively low dose (eg, COVID-19), then their product will achieve a higher log reduction than if compared to an organism that is harder to kill (eg, MRSA).

Moreover, if the statement is made without reference to an organism, then it is almost meaningless (see the following examples).

 

• Details should be requested (burden of proof rests with manufacturer)
• Inquire about the log discount on whatever body (does it apply to you?)

 

The clock is ticking! Time is a factor in disinfection!

UVC dosage is a relatively simple calculation and is entirely based on duration, or more simply, time.

While all manufacturers recognize that time is important as it affects the availability of the rooms and areas you want to disinfect with UVC, it is directly related to the power (amount of UVC) the system can produce.

Faster is not necessarily better, doing only partial disinfection to reduce cycle time means that only a certain number (or type) of organism will be destroyed.

 

Questions to consider

• • How accurate is the time calculation?
  • What methodology do I use? Timer? Camera scan? Reflected dose? What are the tolerances for error (both mechanical and human)?
  • When is time calculated?
  • At what point is the time calculated? Before the cycle? During the cycle?
  • Why is their timing better than other systems?
  • Is the time calculated in the room? Off camera? From a stage / table or based on room size, in real time?
  • For which organism are they aiming to deliver a terminal dose? SarS Cov-2? MRSA? C-Diff?

UVC safety – Disinfection under safe conditions for users

UVC is a low-risk light source, however, no person should be in the room during the disinfection cycle. As such, it is strongly recommended that you check whether the system you are considering is safe to use. The system must have been exhaustively tested and rigorously designed to ensure safety at all times and should feature the following active safety systems.

UVC safe – Stable structure

The base should be wide and heavy enough to ensure there is no risk of tipping over and should be able to easily cross thresholds, bumps or cracks. Casters should ideally feature both a directional brake and a movement brake, ensuring your system stays where it needs to be.

UVC Safety – Motion Detection

The most important feature to be integrated is the PIR (heat and motion) sensor. Ideally, it should be embedded above the level of obstacles, and all these sensors should provide full control over the entire system in the event of a person entering the space where the device is in operation. Any movement when the system is operating will result in an instant shutdown (as well as the system not allowing you to start a cycle if people are detected in the room).

Safety is paramount above all other requirements. Ask for details on active safety systems, how they work, response times, sensitivity, autonomy and effectiveness.

 

Dimensions

In a nutshell, will it fit where you intend to use it? Make careful to inquire about size, weight, and so on, but the most disregarded requirement is height. Make sure the gadget is tall enough to radiate above beds and furniture, but small enough to fit in elevators and narrow hallways.

Checking the size of the car against the footprint of a wheelchair is a useful indicator because it allows you to utilize existing accessibility routes.

Service and support

Service is everything. Whether your product is very expensive or very cheap, at some point you will need to contact support and after-sales service. This could be in the form of training or technical support, or it could be in a failure scenario.

Remember, when you choose a product, you are also partnering with the service provider for a long time. Making the right choice is the key to a smooth integration of UVC disinfection into your workflow.

It is vital to consider both the service aspect and the performance and cost of the system itself. Choosing the right partner for you will make a huge difference in the long run.

Evidence to justify the purchase

When you choose a UVC disinfection system, you choose it for an objective reason, you need to disinfect an area or an object.

For this reason, it is critical to ensure that the products you are evaluating have product-specific supporting data; this simply comes down to the large number of variables in UVC disinfection systems, some of which are previously mentioned. Reflector performance, tube type, power, dose calculation, etc. all have a profound effect on the actual effectiveness of the product to meet your needs and provide terminal disinfection.

The data provided by the manufacturer/distributor should be:

• Helpful
• Clearly defined
• Refer to product performance, not just technology in general

Don’t hesitate to request a demo to see how UVC disinfection can actually be done – where you can evaluate the product and run lab tests to prove the information provided by the manufacturer/distributor.

• Concise and clear – objectives should be outlined at the outset and outcomes clearly defined; and
• Use a recognized methodology – using test protocols that are standard industry practice.

Ask for clarification, check validation, and don’t be afraid to ask for answers!

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We are Wolf-e Robotics, and every day we work to support our mission of disinfecting the air and surfaces in the places where we work, learn, and spend our time. Through disinfection with intelligent UVC light equipment and mobile UVC robots, we provide the most efficient and environmentally friendly method of inactivating microorganisms on surfaces and in the air. With applicability in the medical, commercial, transportation, education, and corporate sectors.

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