If you’re tempted to buy your own UVC lamp, be aware: Lots of gadgets promise to kill germs, including handheld devices that claim to sanitize your stuff in 10 seconds. “Some folks kind of view it as a magic wand or a lightsaber out of Star Wars. You take your UV wand and you wave it over your garbage bag,” says Jim Malley, an environmental engineer specializing in UV at the University of New Hampshire. “That’s unfortunately a gross oversimplification.”
How well UVC kills microbes depends on where it is positioned, how intense it is, and how long the space is exposed—that’s why a weak wand you buy on Amazon might not do much to protect you. But intensity also creates potential for harm; looking directly at a UVC light can cause temporary but painful eye damage.
Far UVC—a shorter wavelength than traditionally produced by UVC lamps (222 versus 254 nanometers)—is emerging as a potentially safer version. It kills microbes but poses less risk from exposure because it’s less capable of penetrating the outer layer of dead skin or the tear layer on the surface of the eye. In a 2018 study, physicist David Brenner, director of the Center for Radiological Research at Columbia University, generated influenza droplets similar to the ones released when we breathe or cough, and he showed they could be inactivated with a low dose of far UVC. He found a similar result with common coronaviruses, as he reported in an April preprint article.
Brenner envisions far-UVC lamps as tools to make airports and airplanes safer. If UVC lamps had been positioned to clear the air around travelers, he says, “perhaps we could have prevented or limited this Covid-19 pandemic.”
Stopping Covid-19 now that it is in 93 percent of the nation’s counties is much more daunting. The CDC notes that the virus can stay viable on surfaces for hours to days, and someone with Covid-19 can spew contagious droplets and possibly smaller aerosols when they talk or cough, but scientists don’t know how long the air remains infectious. With incomplete information about the hazards of transmission, “one downside is that these approaches won’t work at all, that they are maybe targeting the wrong places,” says Blaser, the Rutgers infectious disease researcher.
Architect Kevin Van Den Wymelenberg has a strategy to figure out where we might be exposed to the virus. He has just launched a project to test buildings for SARS-CoV-2 by swabbing surfaces, air filters, and air return grills. It’s like doing a health check for the spaces we occupy. Van Den Wymelenberg began by testing buildings at the Oregon Health & Sciences University and the University of Oregon, where he directs the Biology and the Built Environment Center. The sampling may help university officials monitor the campus when it eventually reopens. (Similar environmental surveillance projects have been launched by other groups to swab subways and hospitals.)
Van Den Wymelenberg also plans to offer a testing service to building owners and managers as a way to diffuse anxiety about public spaces and to track outbreaks. Initially, a kit and the processing to test 12 sampling sites will cost $2,500; Van Den Wymelenberg hopes other universities around the country will join the project, which may lower overall costs. “You can’t test every person every day,” he says. “But comparatively, it’s an order of magnitude easier to test the air handler. You might gain knowledge of 100 people with that one swab.”
Van Den Wymelenberg also has advice about making buildings safer that goes beyond killing germs. The things that enhance our indoor space—fresh outdoor air, sunlight, filtration, and ventilation—also reduce transmission risk. You can diffuse the concentration of a virus in the air just by opening a window, he says. If that’s not possible, HVAC systems can bring in more outdoor air and, ideally, exhaust the air at the ceiling. Keeping indoor humidity in a range between 40 and 60 percent also makes it harder for the virus to spread, he says.
Breathing healthier air in the office—that’s a strategy to lower our chance of catching something from a coworker, whether it’s Covid-19 or just the common cold.
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