We’re all familiar with the term heat rises. Natural convection air currents rise. Upper room, or upper air, ultraviolet germicidal irradiation (UVGI or UV) takes advantage of this with UV devices mounted on or near ceilings. As airborne—aerosolized—infectious pathogens rise toward the ceiling (think of smoke rising) they can be destroyed with UV-C rays emitted by the mounted unit. This principle is relatively simple but for maximum, effective disinfection, and for humans (and animals) to be able to occupy the space with the UV-C rays, there are a couple of key caveats.
The Rise of Aerosols
When we sneeze or cough some of the expelled droplets, which contain viruses, may be larger in size and quickly drop to surfaces where they can be eliminated with normal surface cleaning procedures, but the smaller droplets can travel farther and stay in the air longer. Moreover, the number of particles expelled can grow exponentially. You may see just the large droplets, but approximately 3,000 droplets are expelled in a single cough and as many as 40,000 are expelled in a sneeze. (Source). There has been a loud and growing consensus that there may be more of these smaller airborne droplets, or aerosols, that travel farther and linger longer than has been traditionally accepted. Learn more on our UV Research & Studies page. Eliminating these aerosols circulating through the air is a key strategy in infection control which is where upper air UV comes in (with those caveats).
Maximizing Upper Air UV
In a news report earlier this year, Dr. Donald Milton, an environmental and occupational medicine physician and faculty member at the School of Public Health, University of Maryland, addressed the question of what can be done to better protect us against infectious aerosols. Dr. Milton, an expert in occupational medicine, environmental medicine, public health, toxicology, aerobiology of infection, and environmental health, said that he found in his studies of influenza that what indoor environments could do (he specifically referenced grocery stores and malls) is put “germicidal lights as well as ceiling fans (to) suck up the air.” (Source). This is the scientific principle behind Aerapy’s patented Zone360 which takes this basic idea and maximizes its efficacy.
The patent for Aerapy’s Zone360 upper air UV product was awarded for its unique hybrid system for disinfection. The ceiling-mounted unit disinfects by drawing (sucking up) air directly into its UV system via an integrated fan while also disinfecting additional air circulating anywhere within a 360-degree zone of irradiation created by the unit’s UV-C rays. Further, unlike other upper air UV units, the Zone360 is a ceiling-mounted unit, not wall-mounted, helping ensure 360 degrees of air sanitizing. The Zone360X takes it even further with an included remote control and the option of three fan speeds—created for spaces where occupancy may fluctuate during the day (e.g., restaurants and bars). As occupancy increases, increase fan speed for faster air disinfection. Crucially, the Zone360 upper air UV units with integrated fan continue to draw up and circulate the air when an indoor space’s HVAC or ventilation system isn’t running, eliminating the risk of stagnant times when air and heating systems are not operating.
Upper Room UV for Occupied Spaces
In addition to maximizing upper air UV disinfection with the drawing power of a fan, UV-C rays should stay positioned well above the heads of room occupants. The Zone360 achieves this with louvers to collimate the rays, that is, they remain elevated and parallel to the floor below so there is no risk of the rays directing downward.
Study-backed note: The Zone360 was used in a three-year field study that resulted in an 87.1% reduction in upper respiratory infections (URIs) in the study’s animal subject. The study appears in the November 1, 2020, issue of JAVMA.
For more information on the Zone360 and upper air UV disinfection, contact us.