As schools prepare to resume classes this fall and more of the economy reopens even as the coronavirus pandemic worsens, America's biggest public utility is backing a decades-old technology that could zap the virus pathogens out of the air in public places to help limit the spread of the infection.
The Tennessee Valley Authority is offering financial aid for schools, restaurants, nursing homes and other buildings with public places to install ultraviolet germicidal irradiation lights in air ducts to minimize the spread of airborne microorganisms such as COVID-19.
The technology uses UV-C light, which is a short wavelength ultraviolet light much like concentrated sunlight for disinfection.
TVA had been developing a program to promote UVGI lights to help fight influenza and other airborne illnesses in the next year and decided last month to expedite the roll-out to aid in the battle against the coronavirus.
"As the largest public power provider in America, a key focus for TVA is helping to keep our children and the public safe by supporting technologies that are proven to kill viruses," said Jason Snyder, the manager of TVA EnergyRight. "Schools and businesses realize they need solutions to purify indoor air, and we want to help them install it as they reopen."
Sunlight disinfects, and the UV part of its spectrum is particularly effective at knocking out airborne pathogens, Snyder said. Portable ultraviolet units have used that part of the light spectrum for decades to sterilize surfaces in hospital rooms and subway cars, but portable units can be used only when those spaces are unoccupied. UV-C light can harm humans, as well as kill the virus, for those who are in its direct path.
To help purify the air from the virus without exposing humans to harmful intense ultra-violet light, the UVGI lights are installed within metal air ducts and kill the virus as the air is circulated into heating or air conditioning units.
History of UVC fighting viruses
Ultra-violet light has proven to kill viruses for more than a century.
In 1941 when measles swept through schools around Philadelphia, ultraviolet fixtures were installed at the Germantown Friends School and about 15% of children who had not previously contracted the disease became sick. In the upper-grade classrooms in the same city where ultraviolet fixtures were not installed, more than half of the susceptible students contracted measles.
Despite the long history of success in killing air-borne pathogens, the cost of installing UVGI lights in an HVAC system will likely be a barrier to market adoption. Installing commercially available fixtures for a warehouse-type store like Walmart could cost about $100,000, and Snyder said installing UVGI lighting in air ducts at most schools could cost $50,000 or more.
The ultra-violet light bulbs also have to be replaced about every eight to 16 months, Snyder said.
"But we think even before the coronavirus, it would have been worth the expense for some schools because this technology is also effective in helping to limit the spread of the flu virus and other airborne illnesses that have forced some schools to close in the past and has reduced school attendance in many instances," Snyder said.
Energy Right incentives
Through its Energy Right program that has assisted businesses and households to install more energy efficient heating and air conditioning systems for the past 13 years, TVA is now offering incentives to help pay for the installation of UVGI lights in the metal air ducts to heating and cooling systems to help kill the air-borne virus.
TVA is offering standard incentives at $30 per ton for duct-mounted UVGI systems, which in most instances will pay for about one fourth of the cost of such a system.
John Colmer, owner of Computer Environment in Memphis — which distributes and installs UV-lights made by UltraViolet Devices Inc. (UVDI) — said the TVA incentives should help propel the emerging market for new ways to fights COVID-19 and other air-borne viruses. Within the past few weeks, Colmer said he is already taking about installing UVGI lights in a school, a corporate headquarters and several other businesses where people gather to shop, learn or work.
"I think this type of disinfection of air flows can be particularly helpful in any indoor public place where you have a fairly dense population of people in relatively close proximity," Colmer said. "With the high-intensity, ultra-violet exposure, we are able to alter the DNA of the viruses, including COVID-19, to cause these viruses to die."
TVA's program requires certified installers to mount the specialized ultra-violet lights within its preferred contractor network, which already has more than 80 contractors across the Tennessee Valley prepared to do the UVGI installations.
The vendors of the UVGI lights indicate that about 96% of the virus is killed in the first pass through an air duct and over 99% is killed over time as the system continues to operate. In a typical business environment, there are about six recirculations of air in a typical hour of HVAC operation, Snyder said.
"We have struggled in the past to see this highly effective, very safe technology fully implemented for airborne infections," Dr. Edward A. Nardell, a professor of global health and social medicine at Harvard Medical School, told The New York Times. "We've done the studies. We know it works."
The U.S. Centers for Disease Control and Prevention recommends the use of Ultraviolet Germicidal Irradiation (UVGI) as one of the effective technologies to minimize the spread of airborne microorganisms.
The technology is not a total solution, however, since the virus can still be spread directly from one person to another through being too close to one another or sharing virus-contaminated tools, pencils, papers or other materials.
"We're not trying to say that UV lights fix this entire problem, but it is another tool in the tool shed along with the CDC recommendations for social distancing, wearing masks and washing your hands," TVA spokesman Scott Fiedler said.
Snyder said TVA is the first U.S. utility to offer such incentives to promote UVGI lights, which he said is part of TVA's efforts to get the valley back to work and to promote innovative solutions to problems.
TVA has budgeted $500,000 in the fiscal year that ends Sept. 30 for the UVGI lighting incentives, which Snyder said he hopes will help encourage more installations of the virus-killing systems across TVA's 7-state region.
"If this is really popular and is making a difference, I'm sure that TVA will try to do even more," Snyder said.
Contact Dave Flessner at firstname.lastname@example.org or at 757-6340