If you follow the guidance from the Centers for Disease Control and Prevention (CDC), you have been wearing a bubble when you leave your home. This bubble is invisible, porous, and extends precisely six feet in all directions. Alone in your bubble, you may feel safe, as though if you speak to someone seven feet away, SARS-CoV-2, the virus that causes COVID-19, won’t find you. Take a step closer, though, and you’re in danger.
The six feet rule has hardened in our imaginations. Six feet is what counts as social distancing. As indoor dining, bars, and gyms reopen at limited capacity through New Jersey, signs read to keep six feet away from others. Tables are spaced no less than six feet apart. Where six feet is impossible, everything from plexiglass to plastic wrap shields us from one another.
Unfortunately, this guidance is wrong.
We started spacing ourselves out before we knew how the virus spread. In the absence of data, leaders assumed the virus hitchhiked on contaminated surfaces and respiratory droplets exhaled by infected people — common modes of transmission in past outbreaks.
The World Health Organization (WHO) recommended that people keep a distance of 3 feet, arguing that respiratory droplets typically land within that distance. The CDC recommended the slightly more generous six feet. They got these numbers from papers published in the 1930s and 40s.
With good reason, many scientists suspected the guidance, based on research nearly a century old, to be incomplete. Dr. Edward Friedman, an emeritus professor at Stevens and a well-connected physicist, was one of them.
“I didn’t believe the guidance because there was no science,” he said. When Dr. Friedman spoke with friends, among them Nobel Prize winners and leaders at notable science organizations, he found the same suspicion.
As early as April, research began to emerge that challenged the WHO and CDC stances. Dozens of studies found droplets to travel well beyond six feet, sometimes as far as 26 feet in the direction of a cough. In a hospital, SARS-CoV-2 particles managed to travel 13 feet. In another study, the virus remained suspended in the air for several hours. Scientists alleged that the droplet theory alone could not explain reported outbreaks with limited direct or indirect contact. Aerosols, however, in combination with droplets and surfaces, could explain them.
Aerosols are created like droplets, only far smaller. Too light to settle to the ground, aerosols ride on air currents. They snake around corners and makeshift barriers like smoke, eventually filling the room they occupy. Unlike large droplets caught in the upper respiratory system, aerosols slither deep into the lungs where the virus embeds and multiplies. This is hardly surprising. Aerosols have been found to transmit other viruses, including SARS, MERS, and H1N1.
Dr. Friedman began an ever-growing list of studies confirming the aerosol transmission of SARS-CoV-2. He shared this list with notable connections, ever more convinced of the error of the CDC and WHO. He hoped that by sharing knowledge on aerosols, he could compel leaders to embrace better, science-based policies.
Scientists around the world did the same. In early July, 239 scientists from over 30 countries wrote an open letter to the WHO urging the international body to update their pandemic guidelines.
“Hand washing and social distancing are appropriate, but in our view, insufficient to provide protection from virus-carrying respiratory microdroplets released into the air by infected people. This problem is especially acute in indoor or enclosed environments, particularly those that are crowded and have inadequate ventilation relative to the number of occupants and extended exposure periods,” the scientists wrote.
The letter came as many US states began to reopen indoor businesses, prompting severe outbreaks and renewed closures. Despite this, the WHO responded in a scientific brief with skepticism, admitting the possibility of aerosol transmission in some cases but doubting it in others. Outbreaks in poorly-ventilated areas could be explained, it argued, by surface transmission and close personal contact. It kept its social distancing guideline at three feet. The CDC, for its part, still denies that long-range aerosol transmission is a concern.
The letter did, however, catch the public’s attention. Media reported widely on the possibility of aerosol transmission, and despite WHO and CDC recommendations, the virus grew wings. The molecule that sent the economy tumbling, that shuttered a world indoors, that killed so many times, was airborne.
When Hoboken Mayor Ravi Bhalla announced early September in his regular COVID-19 update that indoor dining would resume, he added that restaurants should try to “keep doors and windows open whenever possible, and to use fans to improve ventilation indoors.” This is a clear recognition of aerosols.
Yet the Mayor’s update still called for six feet of social distancing. All around, the number persists. We hold opposing beliefs, that the virus is airborne and that six feet will save us.
Six feet has become faith. Whether it will save us or not, it gives us the assurance to carry on with some normalcy. Walking outside, seeing a friend, buying food—acts that now harbor risk—are restored a level of certainty by those six feet. It tells us how to manage risk, to not fear the world, even if the science says otherwise.
But to those managing the pandemic, understanding how the virus spreads can be the key to fighting it. Different modes of transmission take different weapons. Washing hands cannot clear viruses from the air, but we have technologies that can.
As we await a vaccine, researchers at companies and top universities look for ways to control virus aerosols. The most promising include using germicidal ultraviolet (UV-C) lights to destroy virus particles. When properly installed, UV-C light is many times more effective than high-quality air filters at disinfecting indoor spaces.
UV-C has been used for decades to disinfect everything from hospital rooms to elevator shafts to air conditioners to subway cars. It is better at killing viruses than UV-A and UV-B, both emitted by the sun, but its higher energy levels make it harmful to human eyes and skin. To shine UV-C on a whole room, everyone first needs to leave. Otherwise, you must settle for shining light only near the ceiling, a process called upper-room ultraviolet germicidal irradiation (UVGI), which will eventually cleanse the air with proper circulation.
At Dr. Friedman’s suggestion, I joined a webinar on using UV-C light against coronavirus. There a distinguished panel made a strong case for the immediate use of upper-room UVGI in public spaces. The technology is tested, safe, effective, and for sale.
One panelist, Dr. David Brenner, a radiological researcher at Columbia, introduced a promising new wavelength of UV-C light that doesn’t damage human tissue. This light, called far-UVC, has a 222 nm wavelength instead of the usual 254 nm, making it higher energy though oddly less penetrating to human cells. Unlike upper room UVGI, far-UVC is not ready for the market. But once it is, it will be able to disinfect the air and surfaces in occupied rooms.
In the meantime, we should heed the science. Six feet is better than zero feet, but the virus doesn’t care about your bubble. As for Dr. Friedman, at 84, he isn’t taking any chances. He said, “Masks are valuable. Social distancing is valuable. But on a personal basis, I wouldn’t invite you for dinner.”
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