Schools are attempting to figure out how to reopen to the public in the fall. From daycare and kindergartens, to junior and high schools, to colleges and universities, students and parents are going to expect a higher level of cleanliness.
Unfortunately, pandemics do not end in a matter of months, and the COVID-19 coronavirus may not going away anytime soon.
Schools will implement new practices, procedures, and technology to combat the virus. One of these is ultraviolet germicidal light, a technology that has been known about since the late 1800s. UV may provide more promise than any other solution.
Most ultraviolet germicidal (UVC) light never reaches the earth, being filtered out by the ozone layer. But UV bulbs that emit germicidal light have been developed and widely researched, and have been used mostly in medical settings for decades.
Numerous studies have shown the effectiveness of UVC light in controlling airborne and surface pathogens, including viruses, bacteria, mold, and fungi.
These are a few solutions that we think would work best for schools and colleges/universities attempting to open in the fall and reduce the risk of getting students, parents, and staff sick.
Because unshielded UVC light is harmful to human and animal skin and eyes, not all UVC solutions can be used during the day when students and staff are present.
Taking that into consideration, these are solutions that are more "out of sight, out of mind," but provide high levels of UVC efficacy and can reduce airborne pathogens. We'll look at in-room air recirculation units and HVAC in-duct UVC systems.
In Room UVC Air Purifiers
Many classrooms, clinics, laboratories, and offices can benefit from air recirculation UVC units. These devices use a fan to pass air into the fixture and over ultraviolet germicidal light bulbs, providing UV irradiance that can deactivate harmful pathogens. They are designed to be used while rooms are occupied and continuously sanitize air.
Most of these units are equipped with a filter that can catch larger allergens and dust. The UVC bulbs then provide germicidal irradiation to viruses, mold, fungus, and bacteria, which are too small to be caught by a filter.
Room air mover ultraviolet fixtures are one of the most popular types of UVC solution at the present time. They are designed for medium size to large rooms, and can be mounted on floors, walls, or ceilings.
Whole Building HVAC Systems
Different respiratory illnesses affect people at different stages of life, but UVC light is lethal to pathogens that cause a wide variety of illnesses. Installing high output in-duct HVAC UVC fixtures can continuously sanitize air as it circulates through the school or university.
The main benefit for a central ventilation UV disinfection system is that air circulates through hallways, closets, locker rooms, utility rooms, offices, and common areas that would be cost-prohibitive to install room air purifiers in each one.
The HVAC UVC system should be a standard line of defense against coronavirus and other pathogens, and these systems can raise the level of indoor air quality to a higher degree than using only furnace filters.
In addition, HVAC UVC systems can result in better energy efficiency and air flow through the central ventilation, especially if one is installed near cooling coils that can be a breeding ground for microbe buildup.
In addition, some classrooms used packaged terminal air conditioners (PTAC), and UV companies have provided PTAC UVC solutions.
After Hours Surface Disinfection
After the students and staff have left the building, maintenance workers or cleaning companies have an opportunity to come in and provide UV surface disinfection. UV manufacturers have developed a number of solutions for disinfecting surfaces.
Many schools have drop-in ceilings with fluorescent or LED troffers. Recessed troffer UVC fixtures could be installed to provide visible light during occupied times, then switch to UVC sanitizing light when the room is unoccupied. These UVC troffers operate the fluorescent and ultraviolet bulbs on separate circuits, so could be wired to be controlled centrally or have lighting motion sensors connected.
With ceiling UVC fixtures of any style, they should only be used when rooms are empty, but they can provide high levels of disinfection in relatively short amounts of time. Sizing fixtures for a room can be complicated, but they can be disinfected in as little as 10-15 minutes.
Of course, with more time available, lower powered UVC bulbs could be used, which would increase the disinfection time but decrease the cost of the fixtures. But if the lights can be run for several hours overnight, the result would be the same, and air and surfaces in the room would receive ultraviolet disinfection.
Mobile Room Air & Surface Sanitizers
Mobile UVC room units can be a large investment for a school or university, but they can disinfect rooms as fast as the high-powered ceiling fixtures discussed above, and they have the benefit of being portable. They provide 360° ultraviolet germicidal irradiation, as well.
Numerous companies have also sprung up offering after-hours UVC disinfection services, so that may be a less expensive solution for smaller school districts, daycares, and colleges. However, there are some smaller units in the $3,000-$4,500 range that may be within the budget of many schools, especially considering the effectiveness and peace of mind they offer.
Handheld UV Sanitizers
While cleaning and maintenance staff can disinfect most surfaces with chemicals, some items would not react well to liquid or chemical treatments. Electronic and computer equipment come to mind, and schools are more wired than ever. Pathogens can easily settle on a keyboard, mouse, or computer.
The challenge with UVC handheld devices is that most use very little power, so they need to be held over a surface for up to a minute or longer. When cleaning staff have a multiple objects in a room and numerous rooms to clean, handheld UVC disinfection is simply too slow.
Thankfully, higher powered handheld UVC devices are now available that can cut down disinfection times to just a few seconds to reach levels of ultraviolet light that are lethal to bacteria and viruses. The high wattage of these devices make it so they can't be battery-powered, but they are lightweight and can cover larger surface areas.
The Bottom Line for UVC in Schools
The best part about UVC solutions is that they are effective not only against coronaviruses or viruses in general. Germicidal light is lethal to a long list of pathogens that cause respiratory and other types of illnesses.
So by combating COVID-19, school and university administrators will also be providing a healthier environment for all students and employees of the school system, resulting in higher productivity, fewer sick days, and better health overall.
Also, maintenance of UVC air and surface fixtures is relatively simple. They often use UV ballasts and light bulbs that are comparable in price and ease of installation to fluorescent lights, which are installed by the thousands in most buildings. And there are a large number of UV bulb manufacturers, so the market is well-established with major lighting companies.
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