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  • Writer's pictureFred Guerin

COVID-19: Aerosol vs Droplet Transmission

I was fairly certain a year ago that the COVID virus was transmitted through aerosols and not through droplets or touch. An aerosol is a particle of saliva or respiratory fluid that floats in the air and infects us when we breathe it in.

That’s distinct from a droplet. Respiratory droplets are small bits of saliva or respiratory fluids that infected individuals expel when they cough, sneeze or speak. Though they are propelled through the air, they quickly fall to the ground because of their weight traveling three to six feet at most. Not so with aerosols. Aerosol transmission is similar to droplet transmission, except that the bits of fluid are so small that they can linger in the air for minutes to hours. That is why, in spite of precautions like mask-wearing and social distancing, it is still quite possible for the virus to be transmitted.

Initially, my conclusion was based primarily on past coronavirus and flu transmissions all of which are airborne. The current scientific and epidemiological research has corroborated this conclusion again and again. Everyone knows about “super-spreader” events where the transmission of the virus is not by contact or droplets but airborne in a way that is exactly similar to other airborne diseases.

Unfortunately, in BC, Bonnie Henry and the BC Center for Disease control stubbornly refuse to acknowledge what has become very clear to many scientists and epidemiologists: COVID-19 is an airborne virus just like other infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS.

By definition, droplets fall rapidly to the ground and therefore are basically unaffected by ventilation. If ventilation impacts disease transmission, it is strong evidence that the disease is spread by aerosols, as aerosols are the only vector significantly altered by ventilation. This simple fact seems to have been largely minimized or ignored by many governing bodies, resulting in conflicting recommendations. For example, the WHO states that COVID-19 is only spread through droplets but simultaneously emphasizes the need for ventilation in the control of the disease. That makes zero sense.

Ventilation is important in the spread of SARS-CoV-1 just as it is in the spread of seasonal respiratory illnesses, which include numerous other coronaviruses. Ventilation really only impacts aerosols, and so this is strong evidence that aerosol transmission is important in the spread of these diseases. We have no reason to believe that the transmission of SARS-CoV-2 is radically different from other coronaviruses which were transmitted through aerosols.

So why do Bonnie Henry and the BC Center for Disease control persist in claiming that the transmission of COVID is only through droplets and direct contact? Why has she denied the science on aerosol transmission for the past year--even longer than the World Health Organization?

I think it is partly because the response to the problem of aerosol transmission is ultimately structural, not individual. It is much easier to just tell people to wash their hands, social distance and wear masks and leave it at that, rather than renewing public policy, calling for an end to large indoor gatherings and requiring schools, public facilities and other buildings to make sure they upgrade their ventilation systems so that contaminated air is sufficiently replaced with fresh air.

Businesses and government agencies do not want to hear this because it means spending money. This was also why when there were outbreaks at industrial sites (notably site-C) the latter were allowed to 'self-regulate' when it came to precautionary measures. You can be absolutely certain that the Horgan government told Bonnie Henry: "hands off industry".

None of this means that we should stop wearing masks and social distancing--though it DOES mean that the best kind of mask to wear in cases of airborne transmission is not a surgical or cloth mask but an N-95 mask--and we are told that the latter are limited and rather more expensive. They are not in fact limited and they should absolutely be required for those who work in healthcare.

Social distancing makes sense in cases of airborne transmission for obvious reasons that have zero to do with transmission through droplets. The closer you are to someone the more likely it is that you will breathe in what they exhale. Just stand beside a smoker if you are a non-smoker--or someone that just ate a garlic sandwich!!

There are zero cases demonstrating transmission of COVID-19 through surfaces or by hand touching--so while handwashing is a good practice for other reasons, it has no effect on the spread of COVID.

The scientific dogma of droplet transmission persists, even though there is now ample evidence of aerosol transmission. The real way to end COVID transmission is just to STAY HOME! Close schools and workplaces for a full 2 years and institute something like a universal basic income to make sure people can pay their rent and buy groceries.

But in a capitalist economy that depends on desperate gig workers to line the pockets of the super-rich, this sort of social and economic measure is not even contemplated

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