INFECTION PREVENTION & CONTROL
25% of the level at 1 m. Using the same calculations shows that the amount of energy reaching a surface just over three metres (10 feet) from the source is 1% of the original.
Soaps can strip natural oils from the skin.
advantages of UVC disinfection is that large areas can be decontaminated very quickly without any additional intervention. Because UVC disinfection is physical rather than chemical, it means that there is much less chance of pathogens developing any form of resistance.
Despite these advantages, no cost- effective, practical UVC systems were available until recently for routine use in healthcare settings.5
Now, the devices
used in hospitals produce powerful UVC light at the optimum wavelengths to provide fast, broad-spectrum disinfection. These devices tend to fall into two categories: for broad area and high-touch surface disinfection, and disinfection of smaller, portable devices.
Systems designed for disinfection of broad areas and high-touch surfaces can be effective in as little as three minutes. This is more than twice as fast as fogging, and almost twice as effective as traditional cleaning and disinfection alone, in destroying the pathogens that cause healthcare-associated infections. They are an excellent option for on-demand disinfection of high-touch surfaces throughout a hospital, including patient rooms, operating rooms, and bathrooms. Such systems can also be used on patient care equipment, fixtures, keyboards, monitors, and workstations.
UVC is at its most powerful when it hits a surface perpendicularly – at right angles - such as directly from overhead or square on to wall. Any deviation from this angle of incidence will diminish the power. In practice this means that at an angle of incidence of 45 degrees, the surface will only receive around 75% of the energy. At angles between 20 and 30 degrees, the energy levels are reduced by around 60%. Like all electromagnetic radiation, the power of UVC also diminishes rapidly the further away a target surface is from the source, because of the inverse square law. This means that the energy reduces fourfold (ie 2x2 or 2 squared) with each doubling of distance. Alternatively, the intensity at 2 m from a light source is just
Systems delivering UVC must therefore ensure the maximum amount hits the target surface to give the most powerful disinfection. One way to achieve this is to mount the UVC sources on arms that can be positioned independently, and pointed towards, and set as close as possible to, the target surfaces. This ensures more of the UVC produced will hit the surface at right angles, and at the minimum distance to give the best disinfection. When the light sources are mounted on a single, central column that is not easily repositioned, less of the UVC produced falls on target surfaces perpendicularly and from further away. Either way this means the device will be less efficient. UVC systems for portable devices are designed to disinfect items such as tablets and smartphones. These are becoming more widely used in healthcare settings, but they are often used by different members of the nursing or clinical team throughout the day. This means that they are not only frequent- or high-touch surfaces, but that they can also present increased opportunities for pathogens to pass from person to person. There is some evidence that people do not wash their hands after using these devices, or indeed clean the device itself. As with any routine process, the use of these disinfection systems should be simple and quick, to encourage their use. Items to be treated are placed in a secure box, which contains the UVC light sources, safely shrouded from the outside world. This means that they are always close to the items being disinfected, for maximum effectiveness. Because items being treated are always close to the UVC source, these units provide extremely effective disinfection. Items can usually be disinfected in around 30 seconds. Independent tests have shown that there can be an up to 5-log reduction in surface pathogens including MRSA, VRE, MDR-Gram negative, norovirus, and C. difficile spores. This means that the number of microorganisms is reduced by 105 times, or by a factor of 100,000. The power of UVC to damage DNA and cells means that people would be affected too if they were exposed. Devices are supplied with fail-safe features, such as remote control, that prevent close-up activation, and motion sensors that shut the unit down if anyone should approach too closely.
Hospitals and other healthcare facilities have a wider range of infection prevention tools at their disposal than ever before. The choice available means that there is greater flexibility to specify the right combination to meet infection prevention
compliance and reduction targets in the quickest, simplest, and most effective way that integrates with the facility’s other processes. The choices can be complex, but leading cleaning and hygiene suppliers with experience in healthcare will be able to work with clinical, nursing, and housekeeping teams to devise and implement robust infection prevention policies.
References 1 Centre for Disease Control & Prevention. 2 Teska PJ, Rushworth A, Theelen M, Jongsma J. O018: Evaluation of the efficacy of a novel hydrogen peroxide cleaner disinfectant concentrate. Antimicrob Resist Infect Control 2013; 2 (018). doi: 10.1186/2047-2994-2-S1-O18.
3 Alhmidi H, Sreelatha K, Cadnum JL, Tomas ME, Donskey CJ. Evaluation of an ultraviolet light device for decontamination of personal items of long-term care facility residents. VA HealthCare, Case Western Reserve University, Cleveland, Ohio, published online.
4 Anderson DJ, Chen LF, Weber DJ et al. Enhanced terminal room disinfection and acquisition and infection caused by multidrug-resistant organisms and Clostridium difficile (the Benefits of Enhanced Terminal Room Disinfection study): a cluster-randomised, multicentre, crossover study. Lancet 2017; 389 (10071): 805-14.
5 Tomas ME, Cadnum JL, Jencson A, Donskey CJ. The Ebola Disinfection Booth: Evaluation of an enclosed ultraviolet light booth for disinfection of contaminated personal protective equipment. VA HealthCare, Case Western Reserve University, Cleveland, Ohio, published online.
Tinaz Ranina
In her role as Product manager for Building Care, Personal Care, & Infection Prevention, for Diversey in the UK & Ireland, Tinaz Ranina is responsible for marketing the
company’s healthcare and infection prevention products. Recent innovations she has helped to launch include the Moonbeam 3 UVC system for fast broad-area disinfection of high-touch surfaces, and the latest generation of Oxivir cleaners and broad-spectrum disinfectants containing Accelerated Hydrogen Peroxide (AHP). Working with Diversey since 2011, she has an MBA from the University of Wollongong in Australia.
October 2019 Health Estate Journal 93
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