Covid Is Airborne, Scientists Say. Now Authorities Think So,
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A quiet revolution has permeated global health circles. Authorities have come to accept what many researchers have argued for over a year: The coronavirus can spread through the air. That new acceptance, by the WHO and the U.S. CDC, comes with concrete implications: Scientists are calling for ventilation systems to be overhauled like public water supplies were in the 1800s after fetid pipes were found to harbor cholera.

Cleaner indoor air won’t just fight the pandemic. Avoiding these germs and their associated sickness and productivity losses would, therefore, offset the cost of upgrading ventilation and filtration in buildings.The study’s authors, comprising 39 scientists from 14 countries, are demanding universal recognition that infections can be prevented by improving indoor ventilation systems.

They want the WHO to extend its indoor air quality guidelines to cover airborne pathogens. They also want building ventilation standards to include higher airflow, filtration and disinfection rates. A "paradigm shift is needed on the scale of Chadwick's Sanitary Report," they wrote. “No one takes responsibility for the air,” a scientist said. “It’s kind of accepted that the air could be of whatever quality — containing viruses and pathogens.”

~ Speaking, singing

SARS-CoV-2 multiplies in the respiratory tract, enabling it to spread in particles of varying sizes emitted from an infected person’s nose and throat during breathing, speaking, singing, coughing and sneezing. The biggest particles, including visible spatters of spittle, fall fast, settling on the ground or nearby surfaces, whereas the tiniest can be carried farther and stay aloft longer, depending on humidity, temperature and airflow.

It’s these aerosol particles, which can linger for hours and travel indoors, that have have stoked controversy. Although airborne infections, like tuberculosis, measles and chickenpox are harder to trace than pathogens transmitted in tainted food and water, research over the past 16 months supports the role aerosols play in spreading the pandemic virus.

That’s led to official recommendations for public mask-wearing and other infection-control strategies. But, even those came after aerosol scientists lobbied for more-stringent measures to minimize risk. WHO guidance has been amended at least twice since, though the Geneva-based organization maintains that the coronavirus spreads “mainly between people who are in close contact with each other, typically within 1 meter,” or about 3 feet.

~ ‘Nothing magic’

There’s nothing magic about this 1 meter. The closer to an infected person, the higher the concentration of infectious particles and the shorter the exposure time needed for infection to occur. “As you are moving away, the concentration decreases,” researcher said. Infectious aerosols remain concentrated in the air longer in poorly ventilated, confined indoor spaces.

Although a high density of people in such settings increases the number of people potentially exposed to an airborne infection, enclosed indoor areas that aren’t crowded may also be hazardous .

~ ‘Hygiene theater’

The role of airborne transmission has been denied for so long, partly because expert groups that advise government have not included engineers, aerosol scientists, occupational hygienists and multidisciplinary environmental health experts. A false narrative dominated public discussion for over a year. This resulted in hygiene theater while the pandemic wreaked mass destruction on the world.

Some people working in infection prevention and control and related fields have stuck rigidly to beliefs that minimized aerosol transmission, despite evidence challenging their views because “they do not want to lose face,” said Julian Tang, a clinical virologist and honorary associate professor in the department of respiratory sciences at England’s University of Leicester.

We all have to adapt and progress as new data become available,” Tang said. That’s especially true in public health, where official policies and guidance based on “outdated and unsupported thinking and attitudes can cost lives,” he said.

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