High up, near the ceiling in the dining room of his Seattle-area restaurant, Musa Firat recently installed a “killing zone”—a place where swaths of invisible electromagnetic energy penetrate the air, ready to disarm COVID-19 and other dangerous pathogens that drift upward in tiny, airborne particles.
Experts attribute this to a combination of factors: misconceptions about UV’s safety, a lack of public awareness and technical know-how, concerns about the costs of installing the technology, and a general reluctance to consider the role of aerosols in the spread of COVID-19.
Aerosols are microdroplets expelled when someone exhales, speaks, or coughs. Unlike the larger and heavier respiratory droplets that fall quickly to the ground, aerosols can linger in the air a long time and travel through indoor spaces.
When someone catches a virus this way, the process is called “airborne transmission.”
It’s already recognized that the coronavirus can spread by means of aerosols during medical procedures, which is why health care workers are advised to wear respirators, such as N95 masks, that filter out these tiny particles. Yet, there is still considerable debate over how likely the virus is to spread in other settings via aerosols.
WHO officials conceded that more research is needed but maintained that most infections don’t happen this way.
Welcome to the ‘Killing Zone’
At Firat’s restaurant, there are just two visible clues of the new UV disinfection system—a subtle glow of blue light above the black grates of the drop ceiling, and a hand-chalked sign at the door, proudly announcing to diners: “Coronavirus Disinfected Here!”Ceiling fans circulate the air, eventually pushing any suspended viral particles that have accumulated in the dining space through the grated drop ceiling, to the area where UV lights, positioned horizontally, blast them with radiant energy.
Marlaina’s owner gained inspiration and technical assistance from customer Bruce Davidson, a pulmonary physician who was Philadelphia’s “tuberculosis czar” in the mid-’90s. Back then, the U.S. was grappling with a new outbreak of TB that included strains resistant to existing drugs.
“Preventing transmission was the most important part because we had no drugs, no vaccine,” says Davidson, who now lives outside Seattle. UV light proved to be a key strategy back then, and Davidson thinks it can help again: “It really ought to be in most indoor public spaces now.”
To demonstrate the concept, Davidson lit a cigar inside Marlaina’s and showed how the smoke danced upward, collecting in the ceiling space with the UV fixtures.
“If somebody has undetected coronavirus and doesn’t eat with a mask and is talking and so on, the vast majority of their particles are going to get pulled up there into the killing zone and circulate and bounce around,” Davidson said. “Statistically, the risk to other people is going to be very low.”
Understanding Aerosols, Airborne Transmission
UV can be a powerful weapon against an airborne virus, but it can go only so far toward preventing infection. People can still get sick from the larger, heavier droplets ejected via coughs and sneezes. They can directly inhale those droplets or touch a surface contaminated with them, and then touch their eyes, nose, or mouth.UV also doesn’t prevent someone from being exposed to infectious aerosols that have just emerged from an infected person and are lingering quite near his or her body—what researcher Richard Corsi called the “near field.”
Understanding the Technology, Safety
Germicidal UV harnesses a portion of the electromagnetic spectrum that contains short waves of radiant energy, called UV-C. This wavelength is further away from the visible spectrum than other forms of UV light.Think of it as giving the virus a lethal sunburn.
Sliney recommends installing UV in big-box stores, restaurants, and grocery stores, which typically have high ceilings.
“There needs to be vertical air exchange,” he said, as with ceiling fans, so “it’s not just sterilizing the air in the upper space of the room.”
Could UV Make a Comeback?
With interest in UV climbing, there is concern about shoddy products and exaggerated claims about their effectiveness against the virus, said Jim Malley, a professor at the University of New Hampshire who studies public health and disinfection.Consumers should be wary of marketing claims about “UV wands” that can be waved quickly over surfaces or special “portals” that people walk through, he said, because those are probably not correctly calibrated to inactivate the virus and could be dangerous.
Malley said he doesn’t think there’s much of a viable market for upper-room GUV outside health care settings, but he supports installing the technology in the most high-risk settings, such as meatpacking plants and nursing facilities.
“My gut feeling is we should do anything we can in those places because we have a horrendous fatality record” with the coronavirus, he said.
At Firat’s restaurant, the installation was relatively straightforward.
He purchased four UV fixtures (at $165 each), hired an electrician to install the fans, and bought black gridded plastic panels to enclose the ceiling space where the UV is mounted.
Firat still encourages his customers to wear masks and maintain social distance. But he said the UV has become part of the ambiance.
“It’s more modern and clean, and the response is great, absolutely great,” he said.
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