Shedding Light on UV Treatment Effectiveness: A Vital Step in Environmental Disinfection

April 2024

Many buildings and facilities use chemicals to disinfect their environments in an effort to protect personnel. UV devices are gaining in popularity as UV is environmentally friendly and, when properly deployed, can be more effective than chemicals and safe for personnel and the environment*.

*Fickenscher, Marie-Claire, et. al. 2023. Operating room disinfection: operator-driven ultraviolet ‘C’ vs. chemical treatment. Infection Prevention in Practice, vol. 5, 100301.

All methods of disinfection have the lofty goal of disease prevention, and the FDA appropriately limits such claims. The causes of actual infectious disease are multifactorial. Typically tens of thousands of people in a prospective, well-controlled study is required. Studies have been attempted using UV systems and have failed to show effectiveness. At this time, FDA approval of a UV device cannot be interpreted to mean the device can prevent disease.

So how can institutions verify the effectiveness of routine germicidal UV treatments?

Culture Plates

Culture plates are the gold standard. They provide quantitative results by sampling surfaces before and after UV treatment, albeit with a 48-72 hour waiting period for results. By the time incubation is finished, it is likely too late to act on the results.

UV Photochromic Indicators

On the other hand, digital or photochromic UV dosage indicators offer real-time feedback on UV intensity delivered to a target, and users can cross-reference the results with microbial susceptibility data. This method is convenient and timely but lacks direct before-and-after germ-kill data.

 

–  Indicators must be placed flat on horizontal surfaces to assess horizontal exposures for relevant feedback  –

For example, positioning indicators vertically facing a UV unit will demonstrate false levels of effectiveness and only provide a false and potentially dangerous sense of security.  

While alternative methods like ATP testing may seem appealing because they are quick, and provide microbial data, they fail to distinguish between live and dead microbes, making them unsuitable for assessing UV treatment efficacy.

Ultimately, professionals seeking to optimally disinfect their environment want assurance that every surface of the room has been appropriately exposed, with the highest log reduction possible. While the road to proving that a UV treatment can impact infection rates may be challenging, some verification methods can serve to guide us toward safer, more optimized protocols. By clarifying and shedding light on the best available verification tools, we can ensure that germicidal UV remains a valuable tool in the fight to ensure the safest possible environments for all.

 

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