20210524

Sixty-year paradigm shift in epidemiology exposes the aerosol screwup

PSI Blog 20210524 Sixty-year paradigm shift in epidemiology exposes the aerosol screwup

 

Sixty-year paradigm shift in epidemiology exposes the aerosol screwup

 

I know this is a bit off-topic, but not by much. Remember that right after George Floyd was murdered, I wrote PSI Blog 20200601 entitled:

 

Coronavirus Hates the Outdoors”

 

From a few news reports, it had seemed obvious to me that Covid-19 was spread mostly via bad breath, which is only a problem when ventilation is bad and a room is crowded. Subsequent political demonstrations and gatherings resulted in very few Covid cases, with less than 0.1% of the infections from outdoor activity. On the contrary, cases escalated when bars, restaurants, and churches prematurely opened to crowds eager to test the power of prayer and jubilation.

 

Unfortunately, epidemiologists in the USA at first recommended that we not wear masks and that air purifiers with HEPA filters were unneeded in crowded rooms. Then they finally recommended we wear masks of any type, which might be nice for preventing transmission of droplets, but not so nice for preventing reception. For that, you probably would need N95 masks, which were in short supply. They work best because, unlike surgical masks, they can screen out particles as small as 0.3 microns.

 

Below I have a link to a wonderful article that nicely tells the story of another nonsensical mainstream paradigm not unlike the Big Bang Theory I normally rant against. It is worth your time reading. It starts with a fellow named Wells who studied measles in the ‘40s, finding its transmission to be aerosolic. He was heavily criticized because the mainstream down-played aerosol transmission just as it did until recently when Linsey Marr and colleagues unearthed Wells’ seminal work. The cutoff was thought to be 5 microns, and those would drop out of the air quickly. That is where the 6-ft trope came from. That, of course, does no good if the air is filled with <5 micron-particles, which settle according to Stokes Law and tend to float around under Brownian motion for hours and hours.

 

Megan Morteni’s fascinating story is much like the one we are now faced with in our campaign to get rid of the Big Bang Theory. It is not quite as absurd as the explosion of the entire universe out of nothing, but it shows how stubborn otherwise supposedly intelligent folks can be in the face of clear evidence. Science is supposed to reverse its tune when incontrovertible evidence shows up—but don’t count on it. Happily, WHO and CDC, after 60+ years and 16+ months of Covid, has finally and quietly adopted the aerosolic theory. Bet you didn’t hear any grand announcements in the press. I also bet Einstein adoration will diminish similarly when relativity and the BBT fade away. Read now about the mighty, deadly crash of a paradigm that has now met its deserved end:

 

Screwup That Helped Covid Kill

All pandemic long, scientists brawled over how the virus spreads. Droplets! No, aerosols! At the heart of the fight was a teensy error with huge consequences.”

 

A staider article signed on by 39 authors, no less, in the mainstream journal Science put the coup de grĂ¢ce on the no aerosol trope:

 

A paradigm shift to combat indoor respiratory infection

Building ventilation systems must get much better

 

Lastly, remember this from Healthline:

 

“Surgical masks do not provide the wearer with a reliable level of protection from inhaling smaller airborne particles. N95s filter out at least 95 percent of airborne particles.

 

Surgical masks leak around the edge of the mask when the user inhales. When properly worn, N95s have minimal leakage.”

 

In other words, all masks tend to protect others, but only N95s protect the wearer. KN95s are not yet approved by NIOSH. Their quality depends on the manufacturer. Unfortunately, some KN95s really should be labeled N70s.


1 comment:

George Coyne said...

I live in the Lower Mainland of BC. Based on how rapidly the numbers of cases were increasing by February 2020 I was confident that COVID-19 was spreading through aerosols. So I stopped going into buildings other than my home when BC recorded its 8th case of COVID-19 on February 29, 2020. I find it difficult to believe that there were any competent epidemiologists who were not well aware by January 2020 of the strong likelihood that aerosols were the primary mode of transmissions of this virus.