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"UV light" gets used as a catch-all term, for everything from a phone sanitizer to a hospital-grade disinfection chamber. That looseness causes real confusion for sterile processing teams and infection prevention leads evaluating the technology for the first time. Here are three things worth understanding before trusting any UV-C system with high-level disinfection, whether you're working within EU MDR requirements, US CDC and Spaulding-based guidance, or both.
1. Not all UV light is germicidal. The wavelength is what matters
UV radiation spans a wide range, and only a narrow band of it does the disinfection work. A peer-reviewed review of ultraviolet irradiation technology, published via the National Institutes of Health's PubMed Central archive, places the most lethal range of UV-C between roughly 250 and 270nm. with the optimal germicidal wavelength close to 262nm. A wavelength of 254nm sits close to that peak and is the output of the low-pressure mercury vapor lamps most commonly used in germicidal devices, since it is easy to produce reliably. UV-A and UV-B, the wavelengths responsible for tanning and sunburn, do not do this job.
This matters because "UV disinfection" as a phrase says nothing about whether a product uses the right wavelength, at the right intensity, for long enough to actually achieve high-level disinfection. A validated device documents its output in specific, testable terms: wavelength range, intensity per lamp, and the microbial log reduction it has demonstrated against named organisms. UV Smart's D60 Instructions for Use, for example, publishes a UV-C output of 253.7nm and log reduction data across bactericidal, fungicidal, viricidal, sporicidal, and mycobactericidal claims, tested in accordance with EN 14885, the European standard for chemical disinfectants and antiseptics that is widely referenced as an efficacy benchmark internationally. If a product can't point to data like this, it's making a UV-C claim without UV-C evidence.
2. UV-C cannot disinfect through dirt. Pre-cleaning is non-negotiable
This is true of every high-level disinfection method, not just UV-C. UV-C is a surface treatment. According to the same peer-reviewed review cited above. its effectiveness is directly influenced by the presence of organic matter on the item being treated, alongside wavelength, exposure time, and intensity. A device or probe that hasn't been properly pre-cleaned according to its manufacturer's instructions will not be reliably disinfected, no matter how validated the UV-C cycle is, just lik it is with chemical HLD.
This isn't a UV-C-specific rule. It's foundational to how healthcare facilities in the US and elsewhere classify reprocessing requirements in the first place. The CDC's Guideline for Disinfection and Sterilization in Healthcare Facilities, built on the long-standing Spaulding classification, defines semi-critical devices, the category that includes most endoscopes and ultrasound probes, as items that must be cleaned and then high-level disinfected. Cleaning is the first, required step, not an optional add-on. That's why pre-cleaning protocols exist as a hard prerequisite in every validated workflow, UV-C included, and why some facilities add simple verification steps, like a visual check under magnification, to give infection prevention teams extra confidence that the pre-clean was thorough before the disinfection cycle even starts. The device does its job perfectly only when the equipment reaches it clean.
3. Line of sight decides what actually gets disinfected
Because UV-C works by direct exposure, any surface the light doesn't reach doesn't get disinfected: a shadowed groove, an occluded angle, a spot blocked by the device's own geometry. The same peer-reviewed review is explicit about this limitation, noting that UV-C's effectiveness depends on the light's ability to reach organisms in folds, crevices, and undersurfaces where it may not reach at all. This is the most common, and fairest, objection raised about UV-C technology, and it deserves a straight answer rather than a dismissal.
The answer is in the engineering, not in ignoring the concern. Validated systems are designed around this limitation. UV Smart's D60 Instructions for Use documents eight lamps positioned to deliver diffuse light distribution inside the disinfection chamber, and it builds shadow-avoidance directly into the loading procedure: equipment must hang freely, without touching the chamber or casting a shadow on itself, before a cycle can run correctly. That's the difference between a general-purpose UV-C wand and a medical device validated for specific equipment types like channel-less endoscopes and TEE probes. The light still can't bend around a genuine obstruction. No UV-C system can. But chamber design and correct loading are what determine whether that's a real limitation for your equipment or a solved problem.
When you're evaluating systems ask about the chamber. How is it designed, does it hang closer to one side than the other, etc. Compare the design to UV Smart's patented Impelux™ technology.
The takeaway
UV-C is a precise technology that is focused on delivering: the correct wavelength, properly pre-cleaned equipment, and a chamber engineered and loaded to deliver validated coverage. Ask any system you're evaluating for their log reduction data, their pre-cleaning requirements, and their validation methodology for line-of-sight coverage. If they can answer all three clearly, whatever market you're evaluating them in, you're looking at a real high-level disinfection system, not just a light.
Make sure you don't fall for tricks like saying IIa vs. IIb classification makes UV-C non-compliant or, even worse, saying you cannot use probes after they've been previously high-level disinfected or pre-cleaned with chemicals. These are scare tactics used to prevent teams to properly evaluate new technologies from us and other UV-C organizations.
If you have questions about compatibility, guidelines or any other roadblocks for a true evaluation, please contact us and we will share data directly from government entities or authorized authorities.
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