According to renowned Harvard researchers, by the time we reach 80, we will have spent 72 years of our lives indoors. This staggering fact means that healthy indoor environments and indoor air quality (IAQ) matter. Furthermore, facilities leaders responsible for the indoor spaces where we spend our time play an instrumental role in stewarding our health and well-being.
We go to great lengths to ensure that everyday resources and spaces are clean and sanitary. In 2017, U.S. spending on water supply and wastewater treatment totaled $113 billion. In 2020, the size of the U.S. surface disinfectant market was $1.1 billion. By contrast, the largest recent amount that the U.S. government has invested in ambient air quality has been $50 million through the Environmental Protection Agency (EPA) and the American Rescue Plan (ARP). Imagine what would happen if we applied the same standards of cleanliness for water and surfaces to the air we breathe in shared indoor spaces like schools, senior care facilities, offices, gyms, and restaurants?
One of the most powerful methods to achieve cleaner air and fight airborne illnesses is something that surrounds us every day: light – specifically, ultraviolet (UV) light.
Did you know UV light can kill or neutralize harmful pathogens in the air and on surfaces? Scientists discovered this capability over 100 years ago. In this article, we’ll explain the basics of UV light and how UV disinfection can protect us from common illnesses, like COVID-19.
The Basics of Ultraviolet Light
UV light is a form of electromagnetic radiation that falls along a spectrum determined by wavelengths. From longest to shortest wavelength, this spectrum includes radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays. UV light naturally occurs as sunlight but can also be created artificially. UV light has three types: UV-A, UV-B, and UV-C. While UV-A and UV-B light can pass through the Earth’s atmosphere, UV-C cannot due to its shorter wavelengths. UV-C light has wavelengths ranging from 100 to 280 nanometers (nm).
The Germ-Killing Power of UV-C Light
Since the early twentieth century, scientists have known about UV-C light’s germicidal (germ-killing) properties. In 1903, Danish doctor Niels Finsen received the Nobel Prize for Medicine for his use of UV-C light to treat lupus vulgaris, a tuberculosis infection that manifests as lesions on the skin. Since then, UV-C light has been proven to destroy or inactivate bacteria and viruses, including SARS-CoV-2, E. coli, and influenza.
UV-C light breaks through the outer membrane of microbes like yeast, mold, bacteria, viruses, or algae. When the radiation reaches these organisms’ DNA and RNA, it disrupts vital cellular function, like replication, thanks to pyrimidine (and thymine) dimers. These molecular lesions interrupt base pairing during the DNA and RNA replication process. This interruption renders the microbe incapable of replicating and prevents the microorganism from causing infections.
Types of UV-C Light: UVGI and Far UV
Within the spectrum of UV-C light (100-280nm), there are subtypes – ultraviolet germicidal irradiation (UVGI) and far UV – whose use cases vary. UVGI applications most commonly leverage 254nm UV-C light to enable air disinfection in one of two ways. Upper room UVGI creates a zone of irradiation in the upper room portion of an occupied space to disinfect air safely above the heads of room occupants. By contrast, in-duct UVGI applies this same irradiation to disinfect air while it is still in HVAC ducts.
Far UV applications most commonly use 222nm UV-C light to disinfect the air and surfaces in an occupied space. Unlike other UV-C light, far UV is a shorter wavelength that does not penetrate human eyes and skin. It is therefore safe for human exposure and can be used in rooms where people are present while still killing airborne and surface-borne pathogens.
Experimental Proof for UV-C Disinfection
Following Niels Finsen’s discoveries of the curative powers of UV light, others found ways to use the germicidal properties of this radiation. In 1910, the city of Marseilles in France leveraged UV light disinfection technology to treat river water. In the 1930s, scientists applied this science to air to control the spread of airborne pathogens. Notably, William F. Wells led research in suburban Philadelphia day schools to understand the efficacy of installed UV radiation lamps as a way to combat the spread of measles. Wells and his research team reported, “There has been no epidemic spread of contagion among the highly susceptible groups of children of the primary schools within irradiated atmospheres.”
While subsequent efforts to replicate Wells’s study failed in the 1940s and 1950s, those failures did not deter R.L. Riley of the Johns Hopkins University School of Hygiene and Public Health. In the late 1950s, Riley and five co-authors studied the infectiousness of air from a tuberculosis ward after it was subjected to ultraviolet irradiation. They used guinea pigs as subjects to demonstrate that tuberculosis was passed via airborne transmission. They also proved the efficacy of UV light. After being “intensely irradiated with UV light,” test organisms in the tuberculosis ward air “were killed in passing through the irradiated portion of the [air] duct.” Riley’s later studies on the power of UV light in fighting pathogens during the 1960s and 1970s focused on upper room ultraviolet germicidal irradiation (UVGI) to disinfect air.
Over the course of the current COVID pandemic, scientists have proven UV-C’s ability to combat the coronavirus. In August 2021, a group of researchers published a review of 18 different scientific studies and scholarly papers about how well UV light inactivated or destroyed coronavirus. The researchers concluded, “SARS-CoV-2 and coronaviruses are relatively easily inactivated by UV light, even when aerosolized . . . UV light could be used on highly touched surfaces in crowded spaces, where rapid and efficient disinfection of indoor environments is crucial to control the spread of highly infective agents such as SARS-CoV-2.”
UV-C Disinfection in Hospital Settings
Around the same time that Wells was starting to research UV irradiation in schools, Dr. Deryl Hart at Duke Hospital in North Carolina was exploring uses of UV light for healthcare settings. In a 1936 article for the Journal of Thoracic Surgery, he wrote, “Pathogenic organisms in the air contaminated by human beings are responsible for most of our operating room infections.” By introducing UV radiation into operating rooms to disinfect air, Hart observed zero deaths, zero wound infections, and “unusually smooth convalescence” among patient subjects.
Hart’s research proved the power of UV disinfection in one of the most challenging, high-stakes environments: a hospital. Hospitals have some of the highest disinfection standards in the world. Consequently, disinfection efficacy is critical. Whole-room UV-C systems can be a critical component of hospitals’ layered approach to reducing hospital-acquired infections (HAIs) such as methicillin-resistant Staphylococcus aureus (MRSA).
While traditional cleaning and the use of chemicals play an important role, studies show that these methods alone are only about 50% effective in the patient environment. Furthermore, over 30% of high-touch surfaces are missed. However, UV-C disinfection layered on these methods yields much better outcomes. A study of MRSA samples collected from patient rooms revealed that when manual cleaning was supplemented by UV light disinfection light treatment, the bacterial counts were 93% lower than with manual cleaning alone.
UV-C Disinfection in Non-Hospital Settings
UV-C light is an ideal disinfection solution for facility managers of dynamic environments with high-touch surfaces requiring frequent cleaning. These environments can include schools, office buildings, senior care facilities, entertainment venues, fitness studios, and hospitality destinations like hotels or restaurants. R-Zero currently works with customers in all of these industries to protect occupants from pathogens.
According to R-Zero’s Chief Scientist, Dr. Richard Wade, UV-C is extremely effective at sanitizing air and high-touch surfaces in any space. As the former head of Cal/OSHA and a leading expert on environmental risk management, toxicology, and microbiological and chemical contamination, he is deeply familiar with the steps necessary to achieve effective disinfection. Dr. Wade explains that air, surfaces, and person-to-person contact can spread pathogenic threats, like COVID. Consequently, he suggests that based on the evidence of UV-C’s efficacy, organizations should ask themselves this question: “How do you apply UV in an optimal solution to help you with your problem of disinfection . . . with the objective of reducing disease?”
One way to achieve hospital-grade disinfection in non-hospital settings is to integrate UV-C devices into existing workflows. This integration requires no additional staff or extra PPE. Devices like R-Zero’s flagship product, Arc, even feature embedded LTE chips with GPS connectivity, empowering facilities leadership to monitor usage and compliance remotely. This capability renders the historically invisible disinfection process visible. In addition, UV disinfection of air and surfaces helps reduce the viral load to zero in both occupied and unoccupied spaces.
How to Wield the Secret Weapon of UV-C
The ongoing struggles associated with COVID-19 emphasize how important it is to protect ourselves, our loved-ones, and vulnerable populations in our society from this current pandemic and other harmful diseases. Although important, manual cleaning and disinfecting solutions are only part of the battle. To succeed in the fight against infectious disease, we must combine these manual methods with safe, automated protection of the shared spaces where we spend the vast majority of our lives. This protection ranges from the air we breathe to the surfaces we touch.
R-Zero’s disinfection portfolio protects shared spaces by rendering them clinically clean through the power of UV-C light. These solutions can integrate seamlessly into existing janitorial protocols while delivering total air and surface disinfection and without necessitating costly HVAC system upgrades or chemical use. Increasing the safety of your spaces leads to better outcomes for the people who live, work, and play in those environments. With UV-C technology deployed in their spaces, people can breathe more easily, both literally and figuratively, thanks to the secret weapon of better protection through hospital-grade disinfection.
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