Nearly 250 scientists joined together to encourage the World Health Organization to give more consideration to the possibility that the coronavirus that causes COVID-19 may be spread through airborne transmission.
The understanding of this virus continues to evolve. As we learn more about the virus, the medical community has had to draw many of its conclusions based on the behavior of previous viruses. At first, medical experts believed spread occurred mostly from touching infected surfaces, but then it became clear that, as a respiratory virus, it is mostly contracted by breathing it in, placing the current emphasis on masking wearing.
The medical community had believed that the virus spreads in the air through large droplets that are emitted by a cough or sneeze and usually stay within 6 feet of their source. But earlier this month, 241 medical experts and scientists presented the WHO with a paper called, “It is Time to Address Airborne Transmission of COVID-19.”
In it, they say there’s evidence that the coronavirus can be aerosolized, or transmitted through tiny droplets that transfer just from talking or singing. Further, they said, some evidence suggests the virus can move significantly farther than 6 feet and could hover in the air for a couple hours.
“Studies by the signatories and other scientists have demonstrated beyond any reasonable doubt that viruses are released during exhalation, talking, and coughing in microdroplets small enough to remain aloft in air and pose a risk of exposure at distances beyond 1 to 2 meters from an infected individual,” said authors Lidia Morawska1 and Donald K. Milton in the letter, titled, “It is Time to Address Airborne Transmission of COVID-19.”
Another 239 scientists added their names to the commentary.
They group said more investigation is needed, pointing not only to studies of the current coronavirus, but also the version that caused the SARS outbreak of 2002 and 2003, and other respiratory ailments such as MERS and influenza.
“There is every reason to expect that SARS-CoV-2 behaves similarly, and that transmission via airborne microdroplets is an important pathway,” the authors said.
They also pointed to episodes of “super spreading” that occurred even though the recommended precautions had been taken.
“... airborne transmission appears to be the only plausible explanation for several super spreading events investigated which occurred under [crowded, poorly ventilated indoor] conditions... and others where recommended precautions related to direct droplet transmissions were followed,” they said.
While it hasn’t been proven that the current coronavirus can become aerosolized, these scientists said, “[the evidence] is similarly incomplete for the large droplet and fomite modes of transmission.”
Until we find out more, they recommend certain precautions. Most importantly, they said, ventilation should be improved to minimize the recirculation of air. This could include such acts as opening doors and windows; incorporating airborne infection controls such as local exhaust, high-efficiency air filtration and germicidal UV lights; and avoiding overcrowding. They also recommended consulting guidelines from the American Society of Heating, Ventilating, and Air-Conditioning Engineers, and the Federation of European Heating, Ventilation and Air Conditioning Associations.
“The measures we propose offer more benefits than potential downsides, even if they can only be partially implemented,” the authors said.
Aquatics professionals had differing views on what this could mean for facilities, particularly those indoors.
Kevin Post, principal and studio director with St. Louis-based Counsilman-Hunsaker, believes facilities are still in a good position to keep clients safe. Modern indoor aquatics facilities generally are outfitted with effective air-handing systems, he said. The industry historically has had to work harder than most to provide good air quality, given the struggle to control the moisture that evaporates from pools and spas and to minimize the effects of pool and spa chemicals in the air. Additionally, aquatics facilities are large spaces, usually with high ceilings.
“[I continue to hear] that, if we can offer swimming in a way that people always have 6 feet of separation, then we can still offer that activity,” he says. “However, if we can’t, then we are at risk of spreading COVID-19 because it’s in the air.”
Like many, aquatics consultant Shawn DeRosa has suspected the virus may transmit through smaller droplets. Given the release of this paper to the WHO, he believes the industry should be even more vigilant than before. “I think we have to work under the assumption that this disease could be spread from aerosolized particles,” he said, recommending that facilities do what they can to improve ventilation and bring fresh air into the space.
One thing for sure, both said: This paper only reinforces the need for social distancing and the use of masks.
