The Dark Side of UV Light: What Spores Are Left Behind?
Halosil Blog

Timely insights on whole room disinfection.

HealthcareOctober 14, 2019

The Dark Side of UV Light: What Spores Are Left Behind?

Healthcare facilities such as hospitals, clinics, ambulatory surgery centers (ASCs), hospice homes, and nursing homes are breeding grounds for pathogens. Filled with immunocompromised patients susceptible to infectious materials, they are also home to a high number of healthcare-acquired infections (HAIs). In fact, according to the Centers for Disease Control and Prevention (CDC), about one in 31 hospital patients has at least one HAI on any given day. Additionally, per the 2015 HAI Hospital Prevalence survey, there was an estimated 687,000 HAIs in U.S. acute care hospitals in 2015 and 72,000 HAI-associated deaths.

In an attempt to lower infection rates, a number of solutions have surfaced that eliminate harmful pathogens, such as those involving ultraviolet (UV) light methods. And yet, while UV light offers a hands-free, relatively fast method to kill infectious matter, it also results in disinfection gaps that leave dangerous pathogens and germs behind.
For instance, UV light cannot claim a 6-log kill rate—the rate required for a sporicidal disinfectant that is registered with the EPA—and so leaves dangerous pathogens like those of C. difficile behind. Rather, some experts state it can only achieve a 1-log kill rate, putting it well below the necessary threshold for a true whole room disinfection system.

If UV light systems fail to eliminate pathogens, why are they so widely used today? Oftentimes, it comes down to confusion regarding EPA labels and claimed kill rates. Technically, UV light disinfection products are not required to be approved by the EPA since the approval process is only mandatory for formulated chemical disinfectant substances—not pesticide devices like UV lights. Consequently, the EPA Establishment Numbers on the label of pesticide devices are often misinterpreted as EPA Registration Numbers. This leads to a great amount of uncertainty surrounding the efficacy, or lack thereof, of these systems.

Beyond a lack of approval from the EPA, what are some of the pitfalls of a UV-based disinfection strategy? Let’s take a look at the dark side of UV light:

1. Pathogens Can Survive in Shadowed Areas

Areas like operating rooms and patient rooms often contain equipment of varying size and complexity, which can in turn create a maze of nooks and crannies where pathogens may lurk. While some of these shadowed areas, like the underside of bedrails, pose no challenge when conducting physical cleaning, hand-free and substance-free processes like UV light fail to reach these areas since they use light waves in a “line of sight” fashion. This means that UV systems can only contact, and thus kill, germs that its light can reach. Missing these shadowed areas can result in a sub-par disinfection.

For these reasons, UV light disinfection often has to be performed many times from different positions within the same operating room and/or have very sophisticated dosage-sensing devices that adjust treatment time, either of which tends to increase material compatibility issues with surfaces closer to the light due to overexposure. While this helps cover more area, it takes up more time—all while still missing pathogens—which can be inhibitive to high-traffic areas like operating rooms that need to be disinfected quickly for incoming patients.

2. Efficacy Weakens with the Distance Between Lights & Surfaces

In order for UV light to be effective against pathogens, it needs to be delivered at the correct frequency as well as at the right intensity. In other words, not only do pathogens need to be in the direct line of sight to receive disinfection from UV light systems, but they also need to be very close to the light source. That said, the intensity of UV lights decreases by the square of the distance, and as a result, so does its efficacy. For instance, a surface at four feet receives only 1/4 the intensity of a surface at two feet, and a surface at eight feet only receives 1/16 the intensity as that surface at two feet. Therefore, a kill test done at two feet is not reflective of what happens at eight feet, even without the effect of shadows.

This means that at double the distance, UV light will only have 1/4 of its power compared to its original reference point. This dynamic limits UV light’s efficacy in distance as it becomes too weak to provide adequate disinfection at great lengths. Consequently, UV light disinfection has to be performed many times from different positions in order to receive its full disinfection effect.

3. UV Light Bulbs Diminish with Age—as Does Disinfection

Finally, while UV light bulbs tend to have lifespans that can last over 12 months or 9,000 hours, by that time, the source intensity has dropped to only about 85% of new bulbs (assuming proper care and routine cleaning have been maintained). Factors like overheating, dirt, and dust on bulbs can also increase the decay of a bulb’s lifespan and thus reduce its efficacy. While the replacement of these bulbs is not expensive, it is also not obvious to users when the bulbs are failing since they continue to emit visible light normally. Together, these factors allow UV light systems to leave dangerous pathogens unknowingly behind.

Look on the Bright Side of Whole Room Disinfection

Where UV light leaves many pathogens lurking, the right dry-fogging approach achieves uniform, sporicidal efficacy across healthcare environments. At Halosil, our Environmental Protection Agency (EPA)-registered HaloMist™ is a hospital-grade disinfectant that eliminates a broad spectrum of microorganisms like C. difficile with a proven 6-log kill rate. By using a dry-fogging delivery, our Halo Disinfection System® offers a hands-free disinfection option that reaches every nook and shadow present in a healthcare facility, all while preserving the integrity of delicate electronic equipment.

Ready to eliminate infectious pathogens in your healthcare facility? Contact Halosil today.