What to Consider When Purchasing an Ultraviolet Light Disinfection Device

Ultraviolet light disinfection, or ultraviolet germicidal irradiation (UVGI), is a fast-growing and invaluable option for preventing the spread of hospital acquired infections. Since the pandemic of Coronavirus Disease 2019 (COVID-19) caused by the novel coronavirus SARS-CoV-2, more consumers are interested in purchasing ultraviolet light products to disinfect surfaces in the home, office, transit, and other commercial spaces. This demand led to more UV manufacturing companies quickly forming to take advantage of the “opportunity.” While we encourage the utilization of this quick, reliable, chemical-free disinfection method, there is a combination of misconceptions and a lack of technical know-how that can lead to purchasing ineffective devices. Today, with so many UV light options on the market, how do you know what to choose? Here are some factors to consider when purchasing an ultraviolet light disinfection device.

PAY ATTENTION TO WAVELENGTH

Some products sold now that claim to be germicidal are actually the wrong wavelength. Ultraviolet light is divided into UV-A, UV-B and UV-C rays. UV-A radiation is less hazardous than UV-B but is also significantly (approximately 1000 times) less effective than either UV-B or UV-C radiation at inactivating bacteria or viruses. It is the wavelengths in the UV-C spectrum (200-280 nm) which offer the greatest germicidal potential. The peak germicidal output is found at 265 nm, however most high-output UV-C devices produce light at the 254 nm wavelength. UV-B takes significantly much more time to reach the killing capacity of UV-C.  As UV-C light makes contact with pathogens, photolytic processes damage the DNA or RNA code, triggering lethal mutations that prevent them from reproducing properly, causing cell death.

THE THREE Ds: DOSE, DISTANCE, AND DIRECTION

The degree of inactivation by ultraviolet light is directly related to the UV-C dose applied. The UV-C dose is the product of intensity and exposure time. Light needs to contact surfaces at the correct intensity for the correct length of time to get the right dosage necessary to achieve the log reduction needed for inactivation of your target organism. When analyzing a UV-C device, compare the intensity of each unit at a certain distance. This will remove the subjective claims such as effective, fast, etc. with specific and quantifiable claims like “Device X” has an intensity of 180 microwatts per cm2 at an 8-foot distance. Many of the UV-C lamps sold for non-commercial or home use have a very low intensity, so it will require a longer exposure on a given surface area to provide effective inactivation of a bacteria or virus. 

UV-C can only inactivate organisms if they are directly exposed to the light. Therefore, the disinfection of surfaces may not be effective if the UV-C light is blocked or shaded, creating shadowed or hidden areas. Similarly, consider the size of the space or the equipment you are disinfecting because as distance from the lamp increases, effectiveness against microorganisms decreases. You may need to choose a light that is tall or angled to best reach areas of concern. Additionally, you may also consider the use of multiple lights at different angles and heights to maximize exposure.  If only utilizing one light, it may be necessary to relocate it to multiple locations in order to maximize UV-C exposure of surfaces within the space.

HANDHELD UV-C WANDS

Some ultraviolet light companies sell handheld wands for swiping over surfaces to kill organisms. Such products are easy to find on sites like Amazon and eBay, and their product descriptions are definitely alluring. However, problems with the wands outweigh any potential disinfection benefits. Regardless of the product, UV-C should not be exposed to skin or eyes as it will inflict a severe “sunburn”. If wands are to be effective, they would need to put out enough UV-C intensity to be very hazardous to the operator. If the wand has a low enough output to be safe for operator presence, it would be too low to effectively kill organisms. Regardless of output, the operator needs to have very precise timing hovering over surfaces in order for a wand to be effective at all. For that reason, ClorDiSys does not sell or recommend the use of UV-C handheld wands.

THE IMPORTANCE OF QUARTZ GLASS

Most glass and plastics have limited to no permeability, blocking the UV-C from disinfecting the surfaces and items on the other side. Quartz glass is the best material for bulbs and any shelving within an ultraviolet light device as it will transmit UV light from 180 nm to 400 nm right through it.  This characteristic allows UV-C to shine optimally and disinfect surfaces sitting on quartz glass shelving, rather than prevent those surfaces from being treated. Some devices utilize metal grills which still provide kill, but not to where the items are sitting on the actual grill wires.

PURCHASE FROM AN EPA REGISTERED FACILITY

Ultraviolet lights that are sold or distributed with claims that the product can be used for preventing, destroying, repelling or mitigating any pest (plant, animal, virus, bacteria or other microorganism) are federally regulated by the Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Generally, without such claims, a UV-C light would not be subject to FIFRA. While UV-C devices do not need to be registered by the EPA and, in turn, are not subject to a premarket review by the EPA, if a manufacturer is making claims of preventing or disinfecting viruses, bacteria or other microorganisms, they could be unfounded. In 2015, the Federal Trade Commission went after two companies marketing UV-C disinfectant devices because of false claims about eliminating foot fungus, methicillin-resistant Staphylococcus aureus, E. coli and Salmonella.  The most trusted UV-C products will be manufactured in a US EPA registered facility.

CONTINUOUS vs. PULSED UV-C 

Some companies claim that pulsed xenon is a more effective way to kill harmful pathogens.  Claiming similarities to a punch of a fist on a wall, more punches will weaken it better than one punch. However, light is not a fist.  Light is a form of energy, and continual energy is more effective than rapidly turning it on and off. The US Veterans Administration commissioned an infection prevention research team led by Curtis Donskey, M.D., to conduct an independent study of continuous ultraviolet disinfection versus xenon pulse UV-C disinfection. The results showed surprisingly low pathogen kill rates for the pulsed xenon device, about .5 log for both C.diff and VRE, even as close as 4 feet.  The continuous UV-C device demonstrated a much higher CFU reduction for the pathogens C. difficile, MRSA and VRE.  The study states, “PX-UV was less effective than continuous UV-C in reducing pathogen recovery on glass slides with a 10-minute exposure time in similar hospital rooms” and “the UV-C device achieved significantly greater log10 CFU reductions than the PX-UV device”.

SUMMARY

With a technology that’s been around for over a century, the efficacy of ultraviolet light against bacteria, viruses, fungi and spores is undeniable. However, in an unregulated market with new products and companies emerging often, consumer education is key. Intensity, bulb length, equipment quality, and price are the key factors to consider. Beware of subjective, attention-grabbing marketing techniques, and compare specific, quantifiable data. Read the product specifications, contact the seller with any questions you have, and if it is incredibly inexpensive, then it is probably too good to be true.

REFERENCES

United States Environmental Protection Agency. (2020, October). EPA Regulations About UV Lights that Claim to Kill or Be Effective Against Viruses and Bacteria. https://www.epa.gov/sites/production/files/2020-10/documents/uvlight-complianceadvisory.pdf

United States Food and Drug Administration. (2020, August). UV Lights and Lamps: Ultraviolet-C Radiation, Disinfection, and Coronavirus. https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medicaldevices/uv-lights-and-lamps-ultraviolet-c-radiation-disinfection-and-coronavirus

Erdmann, J. (2020, August). UV Light Wands Are Supposed to Kill Viruses. But Do They Really Work? https://www.discovermagazine.com/health/uv-light-wands-are-supposed-to-kill-viruses-but-dothey-really-work

Infection Prevention Technologies, LLC. (2015, March). VA Funded Study Validates Continuous UV-C Technology For Pathogen Reduction. https://www.prnewswire.com/news-releases/va-funded-studyvalidates-continuous-uv-c-technology-for-pathogen-reduction-300057832.html

A Spotlight on Stethoscopes as a Transmitter of COVID-19 and Other Pathogens

 All eyes are on healthcare providers in light of the COVID-19 pandemic and an increase in reported cases. More specifically, this added attention has highlighted the shortcomings of facilities’ infection control programs and the lack of education and enforcement for personnel. Some dangerous, but common employee habits include poor handwashing compliance, wearing scrubs out of the hospital, and not cleaning shared equipment. One of the dirtiest pieces of equipment is one that comes into contact with patients regularly, and that instrument is the stethoscope. 

Despite being  used for nearly every patient examination, the stethoscope is rarely, if ever, cleaned before being placed on a patient’s body (yes, yours included). A recent article published in Infection Control Today featured an interview with W. Frank Peacock, MD, FACEP, FACC, FESC that discussed the lack of stethoscope disinfection.  Dr. Peacock explained, “Only about 4% of healthcare providers clean stethoscopes according to guidelines set down by the US Centers for Disease Control and Prevention, and the CDC’s guidelines don’t go nearly far enough, saying that stethoscopes should be cleaned once a week.” While four percent compliance is unacceptable, the CDC’s guideline of only disinfecting stethoscopes once a week is also unacceptable.  In one week’s time, hundreds of patients can come into contact with the device, easily cross-contaminating pathogens between the sick and the healthy.  As Dr. Peacock details, “To do it [disinfect a stethoscope] right, you are supposed to take an alcohol swab and rub it for a minute. And even when you do that, 20% to 30% of the stethoscope will still be dirty.” That low rate of success is not only true for stethoscopes, but other devices and common touchpoints as well.  One example being MIT’s study of smartphone disinfection methods which showed sprays or wipes are ineffective in comparison to ultraviolet light, which was capable of eliminating all organisms on the tested devices without the use of chemicals. 

Ultraviolet light, specifically UV-C, is able to kill bacteria, viruses, and spores quickly.  UV-C’s drawback is that it essentially needs direct contact with all surfaces in order to guarantee high-level disinfection on all sides of an item.  If the light is blocked or shadowed, disinfection of those surfaces is reduced or non-existent.   To overcome those challenges, ClorDiSys Solutions, Inc utilizes quartz glass shelving in the Flashbox and Flashbox-mini UV-C disinfection chambers for items to sit upon. Quartz glass is one of the few materials capable of allowing UV-C light to penetrate through completely, allowing for the full disinfection of the surfaces resting on the shelving.  High level disinfection of a stethoscope or similar item can be as short as 30 seconds depending on the UV-C system being used.  Since no chemicals are used with UV-C light, this allows for a wide variety of items to be disinfected including clipboards, cellphones, keyboards, remotes, badges, blood pressure cuffs, even N95 masks.  

Disinfecting shared devices and supplies like a stethoscope is simple, quick, and truly a necessity when reducing possible transmission of pathogens. As quoted in ACP Hospitalist, Michael B. Edmond, MD, FACP, MPH, MPA states, “Like anything that we're asking health care workers to do, you have to make it easy for them to actually do it, or your compliance rates will be low.” Just as washing hands was once seen as new and optional but now an obvious requirement, hopefully healthcare providers will disinfect stethoscopes just as regularly and thoroughly.