There likely never was a patient zero in the US epidemic — there were multiple. In late 2019, thousands of people disembarked airplanes from China and dispersed. In early March, at least 70 party-goers and choir singers in Connecticut and Washington became infected in separate indoor “superspread” gatherings by airborne transmission. The virus can remain in the air for over 3 hours.
That’s terrifying, but it’s also a vulnerability we can exploit. As the virus spreads through the air, it can be killed in the air with simple, inexpensive Germicidal ultraviolet-C radiation (GUV).
Make no mistake. While important, fighting coronavirus with social distancing and staying home is like fighting an air war without an air force, only bomb shelters.
Unlike influenza, this coronavirus infects lung cells, not nose and throat cells. Coronavirus particles in the nose and throat enter the deep lungs during sleep (aspiration), or at any time by inhaling airborne floating particles exhaled by an infected person. All of us, healthy and infected, can minimize the risk of aspirating coronavirus during sleep by washing our hands, face, and nostrils and gargling/rinsing for 60 seconds with 1.5% hydrogen peroxide mouthwash before bed. But even 6-foot distances won’t protect against inhaling the virus where people gather indoors.
Deep in the lungs of infected people, the particles kill cells and release more viruses. An uncovered sneeze or cough propels thousands into the air. Indoors and in quiet air, most particles don’t get very far, maybe 3-5 feet, before they fall to the ground or a table-top, doorknob or shirt. But they can dry and remain infectious several days on surfaces and be blown airborne again by forced air heating or cooling.
That’s the bad news. The good news is we can kill them in the air. During the 1990s drug-resistant tuberculosis epidemic, the Centers for Disease Control and Prevention (CDC) collaborated with occupational health experts to publish airborne control prevention principles that apply today. Rules of personal conduct – like covering coughs – are important. But so are environmental controls to inactivate airborne viruses.
It is not difficult to remove airborne microbes wherever people gather — in public libraries, waiting rooms, cafeterias, or restrooms where someone coughed hard moments earlier. Exhausting air outside is effective but can sometimes be difficult. The any-season, inexpensive, lasting solution is GUV.
Placed near the ceiling, GUV nearly annihilates microbe infectivity. GUV is a proven potent disinfectant for coronavirus, either in fluid or airborne, and has been used to disinfect surfaces for decades. 16 seconds of ultraviolet-c radiation (UV-C) exposure inactivated 82% of an aerosolized dose. GUV efficacy against highly-resistant TB, which is primarily transmitted through the air, was proven in a multinational-CDC-WHO study. In our Philadelphia TB Clinic in 1993, we also installed inexpensive ceiling fans, run at low speed, switched to pull the air up instead of down, to help assure air mixing and fastest microbe inactivation, an approach endorsed in the 2015 multinational report.
Attention to safety and detail in upper-room GUV installation is required to protect skin and eyes from potential overexposure. High doses of UV-C can cause cancer and cataracts, but accidents are avoidable. Additionally, tests are underway with a shorter wavelength form of UV-C that has so far proven to be harmless to human skin cells while still destroying airborne microbes, making it potentially viable for use in occupied public spaces.
We should prioritize installing GUV now in spaces like ERs, ICUs, dialysis centers and clinics, congregate settings like prisons, followed by any other public and private spaces where the public gathers. Retrofitting is inexpensive. Five-star hotels can buy GUV tricked out like a Cadillac, but GUV is also produced as inexpensive UV-C fluorescent tube fixtures screwed high on the wall in simple ballast fixtures. Bulbs last 9000 hours. Repainting the ceiling with dark non-reflective paint, protective strips or egg-crate ceilings reduce UV-C light reflected below. The total output needed is just 1⁄2 milliwatt per cubic foot. A bar-restaurant or waiting room sized 40’ x 50’ with 8-foot ceilings (16,000 square feet) needs just two 20-inch 15-watt 254 nm fluorescent tube fixtures ($175 each) with a total GUV output of just 8 watts (efficiency about 28%).
Proprietors and building managers should purchase handheld UV-C monitors to regularly monitor and record outputs to assure safety in the room below while GUV does its work on the microbes above. Technological advances are on the horizon, with LED bulbs already in the ultra-high-dose water and equipment purification markets. In the longer term, GUV and ceiling fans in public indoor spaces could become part of building codes, like sprinkler systems. Use them like the heater: Turn them on during fall, winter, and spring virus seasons, otherwise off.
If we want life to get back to “normal,” we should start installing GUV fixtures in public spaces today. While mass gatherings will have to wait, healthcare facilities and owners of public spaces could install UV-C fixtures hardwired or connected to an existing outlet. Coughers and sneezers must stay home or wear masks if they must go out. The rest of us will be back at work, with shops and restaurants advertising “Coronavirus Disinfected Here!”
Bruce L Davidson MD, MPH is a pulmonary physician and researcher in Seattle, expert in respiratory transmission of infection, and former President of the National Tuberculosis Controllers Association and member of the HHS Secretary’s Advisory Council for the Elimination of Tuberculosis.