There is a common misconception when it comes to using ultraviolet germicidal irradiation (UVGI or UV) in schools or any indoor space—that a room cannot be occupied when UV lights are in use. This is false. The truth is, when properly designed, manufactured, and installed, UV equipment can be used to disinfect the air while spaces are fully occupied.

Right now, schools in the U.S. and internationally are using UV in occupied cafeterias, libraries, classrooms, and other gathering areas. In fact, it’s when spaces are occupied—when people are breathing, talking, coughing, sneezing—that UV is needed the most to kill aerosolized pathogens, including SARS-CoV-2, the virus that causes COVID-19, as well as influenza, mold, and more.

For maximum disinfection to help prevent the spread of disease, air should be circulating and the sanitizing UV-C lights engaged while the space is occupied. This is why both the Centers for Disease Control and Prevention (CDC) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), along with other leading authorities, recommend the use of UV, upper-room UVGI in particular, to help eliminate SARS-CoV-2 as well as other infectious diseases.

With unvaccinated children and the lack of mask mandates in school districts across the country, many are asking how to help schools protect children during the school year. Increasing room ventilation is key but also a current conundrum for many schools as previously established protocols require doors and windows to remain closed and locked for security purposes. In its published guidelines for reopening schools in the wake of COVID-19, the CDC pointed to its “Cleaning, Disinfecting, and Ventilation” guidelines which include this direction:

“Use ultraviolet germicidal irradiation (UVGI) as a supplemental treatment to inactivate SARS-CoV-2 when options for increasing room ventilation and filtration are limited. Upper-room UVGI systems can be used to provide air cleaning within occupied spaces, and in-duct UVGI systems can help enhance air cleaning inside central ventilation systems.”

A recent study in Clinical Infectious Diseases, a peer-reviewed medical journal published by Oxford University Press, addressed just how much aerosols—aerosolized pathogens—have caused the spread of SARS-CoV-2. In the early days of the pandemic, the focus was on surface cleaning but, today, much of that effort is considered “hygiene theater,” providing the illusion of protecting against COVID-19 while doing little to reduce risk. A recent report in the CDC’s Morbidity and Mortality Weekly Report (MMWR) demonstrated the impact of aerosolization in schools, citing an outbreak that was traced back to a teacher who was unknowingly infected with COVID-19. The teacher, unvaccinated and unmasked, read aloud in her classroom to her students, all of whom were too young for vaccine eligibility. After exposure to this teacher, 8 of the 10 children sitting in the two rows closest to the teacher’s desk tested positive for COVID-19 and 4 of 14 children sitting on the back three rows tested positive.

While surface cleaning absolutely matters, as it always has, the reality is the unmanaged threat of SARS-CoV-2 remains in the air. For example, the Clinical Infectious Diseases study, “Viral Load of SARS-CoV-2 in Respiratory Aerosols Emitted by COVID-19 Patients while Breathing, Talking, and Singing,” found that, overall, fine aerosols constituted 85% of the detected viral load. Upper-room UVGI used while a room is occupied reduces the viral load, destroying pathogens before they can be inhaled by someone else in the room or settle out on surfaces. In short, sanitizing the air is critical particularly in the face of the Delta variant of the original SARS-CoV-2 strain as it transmits much faster and people infected with the Delta variant produce much more of the virus.

ASHRAE, an authoritative body that speaks to indoor air quality advises that airborne infectious disease transmission can be reduced with in-room airflow regimes and UVGI, among other solutions. Further, they recommend building designers, owners, and operators give high priority to enhancing HVAC systems with supplements including UVGI as it can be applied in new buildings at moderate additional cost and can be applied quickly in existing building systems to decrease the severity of acute disease outbreaks.

To be clear, disinfecting the air with UV—either integrated within an HVAC system or as a standalone, ceiling- or wall-mounted upper-room UVGI unit—includes using it while the space is occupied. The Department of Health and Human Services (HHS), with the CDC and the National Institute for Occupational Safety and Health (NIOSH), published guidelines for, among others, facility designers and engineers on how to install and maintain effective upper-room UVGI. Although written to help prevent the spread of tuberculosis, another disease transmitted by aerosols, the same principles found in the guidelines apply: increasing protection “while maintaining a safe level of UVGI in the occupied lower portion of the room.”

Upper-room UVGI takes advantage of the natural phenomena of rising convection currents (i.e., heat rises). As aerosolized pathogens rise toward the ceiling (think of smoke rising) they can be destroyed with UV-C rays emitted by a unit mounted on the ceiling or upper wall. Aerapy manufactures upper-room UV products with built-in fans that provide immediate, targeted disinfection to help increase air circulation to move air through the path of the sanitizing UV-C.

Using UV to clean the air, particularly using upper-room UVGI, is advanced by a slate of authorities. Moreover, the use of fans is frequently recommended to increase airflow and maximize disinfection. For example, the Clinical Infectious Diseases study’s researchers say the results “underscore the importance of reducing exposure to fine respiratory aerosols through non-pharmaceutical interventions (NPIs).” Included in their suggested NPIs are “upper-room ultraviolet air disinfection, and the use of fans to control airflow patterns within a space.”

In his presentation for “Keeping Public Spaces Safe: Germicidal Ultraviolet Light for Air Sanitation During COVID-19,” presented by the Harvard Kennedy School and Harvard Global Health Institute, Edward Nardell, MD, Professor of Medicine at Harvard Medical School and Harvard School of Public Health, recounted the famous real-world application and study by William F. Wells of using upper-room UVGI to prevent the epidemic spread of measles among children in suburban Philadelphia day schools.

Another interesting study Dr. Nardell pointed to was a 1957-1958 study at a VA hospital in Livermore, California. The observational study showed that in rooms where UV had been installed to help prevent the spread of TB, the rate of seasonal flu was a fraction of that in rooms where UV was not installed. Although not a planned or controlled study, Dr. Nardell said it was “rather convincing evidence” of UV being about 90% effective.

Further, during his presentation, Dr. Nardell addressed the use of fans to help ensure good air mixing in a room to improve the efficacy of UV. This is the scientific principle behind Aerapy’s upper-room UVGI units with built-in fans—no additional fans needed.

As explained by the FDA, UV-C radiation can cause skin burns and eye injuries. This is why direct skin exposure and looking directly at a UV-C light source should be avoided. UV lights used within an HVAC system to clean the air are far from sight, but upper-room UVGI, which is for targeted, immediate disinfection in defined spaces, is used in occupied rooms. How is exposure prevented? First and foremost, remember this is upper-room UVGI—the wall-mounted units are typically installed 7-8 feet above the ground and ceiling-mounted units are attached to the ceiling. Further, the UV-C bulbs are part of a larger unit designed with safety elements. For example, Aerapy’s Zone360 and Zone180 upper air UV units utilize louvers in their design to direct UV rays up and away from the occupants below, while the company’s PSF Series is a contained design. Because all Aerapy upper air units include built-in fans, a feature unique to Aerapy products, this helps circulate the air and aerosolized pathogens through the path of the sanitizing UV-C.

When it comes to COVID-19 and how to prevent its spread, misconceptions have run rampant, but the misconception that spaces cannot be occupied while UV is in use is one misconception that needs immediate correction, particularly when it comes to schools where the masked and unmasked, vaccinated and unvaccinated occupy the same space.

You may be asking, “How can we help protect school children who are ineligible for the vaccine?” or “How can we help protect them in the face of mask mandate uncertainty?” There is no doubt a multilayer approach is needed to help prevent the spread of COVID-19 but, when properly designed, manufactured, and installed, like Aerapy products, UV equipment can be used to disinfect the air while spaces are fully occupied.

Since the start of the pandemic in early 2020, the market has been flooded with products pushed by manufacturers and middlemen new to the UV market. While many of these products have flashy marketing behind them, their efficacy is unproven. Further, UV is frequently lumped together with other purported air cleaning products that may not actually clean the air. For example, a growing chorus of experts say ionization is an unproven—and potentially harmful—waste of money. UV is not ionization. That UV works to disinfect the air and help prevent the spread of infectious disease is well-established and supported by experts. But when it comes to selecting the right air cleaning equipment, make sure potential suppliers have tested their final products with their studies. Educating yourself is crucial.

Since 2008, Aerapy has manufactured researched, tested, and study-backed UV products. Aerapy UV is currently in use in occupied spaces including schools. In independent testing, Aerapy UV technology was found to kill more than 99.9% of tested pathogens including SARS-CoV-2, highly resistant bacteria (MRSA), mold, and viruses covering six key factors for human and zoonotic pathogens. Of notable interest for those with allergies, an independent study by a risk management company found no identifiable spores or smuts (multicellular fungi) in the conference room where they had installed Aerapy UV.

To learn more about Aerapy UV technology for infection control, contact us for a free UV consultation.