Under pressure from the scientific community, the World Health Organization (WHO) acknowledged last week theas a possible third cause of COVID-19 infections.
To many researchers in Japan, the admission felt anti-climactic.
This densely populated country has operated for months on the assumption that tiny, “aerosolized” particles in crowded settings; are turbo-charging the spread of the new.
Very few diseases — tuberculosis, chicken pox and measles — have been deemed transmissible through aerosols.
Most are spread only through direct contact with infected persons or their bodily fluids, or contaminated surfaces.
“If the WHO recognizes what we did in Japan, then maybe in other parts of the world; they will change (their antiviral procedures),” Shin-Ichi Tanabe, a professor in the architecture department of Japan’s prestigious Waseda University.
He was one of the 239 internationalurging the United Nations agency to revise its guidelines on how to stop the virus spreading.
Large droplets expelled through the nose and mouth tend to fall to the ground quickly; Makoto Tsubokura, who runs the Computational Fluid Dynamics lab at Kobe University, explained.
For these larger respiratory particles, social distancing and face masks are considered adequate safeguards.
But in rooms with dry, stale air, Tsubokura said research showed that people coughing, sneezing, and even talking and singing; emit tiny particles that defy gravity — able to hang in the air for many hours or even days, and travel the length of a room.
The key defense against aerosols, Tsubokura said, is diluting the amount of virus in the air; by opening windows and doors and ensuring HVAC systems circulate fresh air.
In open-plan offices, he said partitions must be high enough to prevent direct contact with large droplets; but low enough to avoid creating a cloud of virus-heavy air (55 inches, or head height.)
Small desk fans, he said, can also help diffuse airborne viral density.
To the Japanese, the latest WHO admission did at least vindicate a strategy that the country adopted in February, when residents were told to avoid “the three Cs” — cramped spaces, crowded areas and close conversation.
After a lull, new infections — primarily among younger residents in Tokyo — have resurged recently, topping 200 for four straight days, before falling back down to 119 on Monday.