environmental hygiene
By Jim Gauthier
The Business Case for UV-C Disinfection
Contaminated surfaces play a significant role in the transmission of pathogens . A paper by Jon Otter of the National Center for Biotechnology Information summarized studies that demonstrated different healthcare pathogens that are found in the environment that are shed by patients that can be transmitted to other patients . Organisms included Clostridioides difficile , antibiotic resistant organisms , and viruses .
Frequently touched surfaces are more heavily contaminated and represent greater risk . In a hospital environment , surfaces near patients are often contaminated . Those contaminated surfaces increase the risk of transmission , either directly or through hands of patients and staff . Crowded rooms with lots of activities and poor ventilation can help spread respiratory viruses . Manual cleaning and disinfection is often inadequate , creating increased risk for transmission .
Carling , et al . ( 2008 ) studied cleaning compliance across 23 acute-care facilities and found that overall compliance with key surfaces was 49 percent ( range of 35 percent to 81 percent ), indicating half of high-touch surfaces were not being routinely cleaned during discharge ( terminal ) cleaning of patient rooms . Cleaning compliance varied significantly by surface ( the bathroom light switch was 20 percent and the sink was 82 percent ). Carling ’ s study found a high variability between hospitals , with the cleaning compliance by surface in a different order for each hospital .
Due to time pressures , manual cleaning and disinfection are not being consistently performed to achieve safe environments . A study by the Association for the Healthcare Environment ( AHE ) of environmental services ( EVS ) personnel ’ s cleaning performance in hospitals in the U . S . found that on average , staff spent 15 minutes performing a daily clean of a patient ’ s room and 44 minutes performing terminal cleaning procedures in a recently vacated patient room . Because of time pressures , staff may resort to shortcut cleaning practices , which reduces cleaning compliance . Also , individuals will clean a room slightly differently than their peers , regardless of training received .
In their study , Bernstein , et al . ( 2016 ) found that 30 percent of EVS staff say they don ’ t have enough time to perform daily cleaning and 20 percent state they don ’ t have enough time for discharge cleaning . This can present serious risk to patients admitted into a room previously occupied by a colonized or infected patient .
The Centers for Disease Control and Prevention ( CDC ) recommends “… a multi-barrier strategy to prevent healthcare-associated infections .” In their Hierarchy of Controls ( see figure 1 ), rather than focusing only on improving cleaning compliance ( an administrative control ), adding an engineering control may be more effective , and could help reduce some of the variability seen between different EVS staff .
Figure 1 : Hierarchy of Controls . Courtesy of the CDC
“ No-touch ” disinfection solutions such as UV-C devices work without user involvement to protect from any gaps in current cleaning practices . What ’ s more , UV-C devices have been robustly tested and found effective through more than 40 studies measuring either the biocidal effect of UV-C light on microorganisms or the impact on healthcare-associated infection ( HAI ) rates . UV-C has been proven to kill vegetative bacteria , fungi , viruses and bacterial spores .
Wong , et al . ( 2016 ) evaluated 61 rooms and 360 surfaces for contamination before and after regular hospital disinfection . The authors found that prior to cleaning , 30 percent to 35 percent of rooms tested positive for MRSA , VRE , or C . difficile . Standard patient room cleaning and disinfection had a modest effect as some surfaces were routinely missed , and other surfaces appeared to have been contaminated during the cleaning process . However , the use of UV-C reduced contamination in those rooms to less than 5 percent . Floor bacterial levels were similarly reduced due to UV-C .
Ultraviolet ( UV ) light is a component of the electromagnetic spectrum that falls in the region between visible light and X-rays . It is invisible to the human eye , has been used for decades to disinfect air and water . Killing of microorganisms is most effective at light wavelengths of 254 nanometers . UV light can be divided into UV-A ( black light ), UV-B ( tanning beds ), or UV-C ( disinfection ). UV-C can deactivate DNA ( dimerization ). The physical process does not kill organisms directly , but it will prevent them from reproducing . While UV-C can be used as an effective , environmentally friendly , non-chemical approach to disinfection , it is most effective if surfaces are properly cleaned prior to its application , as UV-C has poor penetration through soils or fabric .
UV light , as electromagnetic radiation , behaves according to set rules of physics . It should be noted that UV light intensity decreases with the square of the distance from the bulb . This means , if 100 arbitrary units of energy were delivered at one foot from the bulb and the distance was doubled to 2 feet , only 25 percent of the energy would be detected ( 2 squared is four , ¼ of 100 is 25 ). And that efficacy number goes down to 11 percent when the bulb is 3 feet away from a surface ( 3 squared is 9 , 1 / 9 of 100 is ~ 11 ). This is physics and not a device issue , as light energy ( photons ) collides with molecules in the air and lose energy .