Some New Science on Virus Transmission on Airplanes

[Mike Banks]

The air conditioning system in use has special medical grade filters able to stop virus sized particles, and if that filter has been replaced later using a much cheaper dust only filter, an aircraft so fitted would have to be a GREAT way to transmit a virus to all on board.

The same as on ships--even passengers who remained in their cabins were affected. It was distributed and dispersed through the ventilation system. The only way to be safe is to wear a hazard suit properly filtered--and no one is providing them--yet.

[Lake-Effect]

Originally Posted by gonesail

believe me .. if you are sick and coughing .. a cloth mask will not prevent you from spreading your illness. and most of us know that a cloth mask will not filter out viral particles that are being expelled from someone else

If you are sick and coughing, or you are asymptomatic but have a good idea you might be infected, you have NO BUSINESS leaving home and mixing with people. Period. Stay home.

If you're asymptomatic but don't yet know it, and you go out, your basic cloth mask will significantly reduce the amount of virus you spread around. That's the idea.

[GordMay]

Originally Posted by Mike Banks

The air conditioning system in use has special medical grade filters able to stop virus sized particles, and if that filter has been replaced later using a much cheaper dust only filter, an aircraft so fitted would have to be a GREAT way to transmit a virus to all on board...

Indeed.
Cabin air quality: Risk of communicable diseases transmission ~ IATA
“The overall risk of contracting a disease from an ill person onboard an airplane is similar t o t hat inother confined areas w it h high occupant density, such as a bus, a subway, or movie theatre for a similar time of exposure. anywhere where a person is in close contact wit h others.
That said, the risk on airplanes is probably lower than in many confined spaces because modern airplanes have cabin air filtration systems equipped with HEPA filters ...”
More ➥ https://www.iata.org/contentassets/f...ir-quality.pdf

[Mike OReilly]

Originally Posted by Lake-Effect

If you are sick and coughing, or you are asymptomatic but have a good idea you might be infected, you have NO BUSINESS leaving home and mixing with people. Period. Stay home.

Definitely! It's funny though... one guy sneezed on the plane three rows up and one over from me. Everyone in the area turned to look. We're all thinking the same thing; is this guy sick? .

Originally Posted by Lake-Effect

If you're asymptomatic but don't yet know it, and you go out, your basic cloth mask will significantly reduce the amount of virus you spread around. That's the idea.

Yes, MarketPlace did a recent study on these. It was pleasantly surprising to find how well the three-ply, higher weave basic cotton masks performed. Almost as good as the standard N95.

These cloth ones are pretty easy to find or make.

[GordMay]

It used to be, that you were embarrassed, if you farted in public.
Now, you're embarrassed if you cough.

[Mike OReilly]

Originally Posted by GordMay

It used to be, that you were embarrassed, if you farted in public.
Now, you're embarrassed if you cough.

Yup . And I always feel the need to say out loud: "It's Not Covid!!"

Oh to live in interesting times .

[GordMay]

Originally Posted by Mike OReilly

Yup . And I always feel the need to say out loud: "It's Not Covid!!"
Oh to live in interesting times .

When questioned (any cough?), I always indicate that I have a chronic smoker's cough.

[Midnight Son]

Originally Posted by GordMay

When questioned (any cough?), I always indicate that I have a chronic smoker's cough.

Yep friend of mine who has a bad smokers cough, was asked to leave the hospital, before he could go in for testing. I pray he does not have cancer.

[AKA-None]

Nothing short of a full hazmat suit will stop everything. But most anything will stop some.

[NPCampbell]

Originally Posted by Mike OReilly

My thermal scan took about as long as it takes for me to take off my glasses. Seconds. Not sure how efficacious it was, but it sure was fast.

Distancing IS a useful countermeasure to the Covid-19 virus. The science is still evolving, but it's clear the majority of viruses are attached to particles larger than aerosol level. Much like the inverse-square law, the majority of this stuff falls to the ground quickly. The further you are away from the source, the better. Two metres has been rather arbitrarily chosen, but does represent a distance where the majority of viral particles will have hit the ground.

It's all about risk mitigation. Nothing is 100%.

I'm not sure that it can be said that a majority of the viral particles hit the ground after 2 meters. The 2 meter distance is based off the Wells Curve from his associated paper written in 1934. 2m was Wells threshold for the max distance traveled by large droplets. Unfortunately it was based entirely on mathematical formulas with no empirical testing. It has been shown to be incorrect by wide margins by numerous studies over the past 85 years. Public health officials seemed to have clung to this distance, possibly due to pragmatic reasons.

[endlesspursuit]

Originally Posted by dannc

No, one should be vaccinating the people most likely to die. The vast majority of people dying from COVID are the elderly and especially those in nursing homes. They should get the vaccine since they are most likely to die from the virus.

But health care workers and other first responders HAVE to get the vaccine first since they are more likely to be exposed, are more likely to be taken out of service and spread the virus. If there are no first responders and health care workers, then the death rate will soar.

After the health care workers and first responders get the vaccine then it should be the must vulnerable group who are dying. Which means the elderly.

One of the two failures in this whole mess is not being able to keep the virus out of nursing homes, which may be all but impossible, and not providing N95 or surgical masks to the general population. Nine months into this mess, and no country that I am aware, has made the effort to increase production of N95 or surgical masks for everyone to use.

Later,
Dan

Actually 3M went into 24/7 N95 mask production way back around March. There is also a company in Texas that runs 24/7 making them as I'm sure there are others around the world. A lot of the shortages you hear about are hype. We use them in construction and they are available.

[Emouchet]

Originally Posted by Dockhead

We haven't really talked about thermal cameras, but it seems to me that this is a really excellent measure.

Thermal camera are not so accurate. Reading body temperature accurately requires a real time calibration to a reference, and even then, accuracy is within +/-2C.

So, considering 37C is normal, and 40C is someone really sick, with a +/-2C accuracy, where do you set the limit ?


Learn-the-limits-of-elevated-body-temperature-screening:
https://www.vision-systems.com/camer...ture-screening

[Mike OReilly]

Originally Posted by NPCampbell

I'm not sure that it can be said that a majority of the viral particles hit the ground after 2 meters. The 2 meter distance is based off the Wells Curve from his associated paper written in 1934. 2m was Wells threshold for the max distance traveled by large droplets. Unfortunately it was based entirely on mathematical formulas with no empirical testing. It has been shown to be incorrect by wide margins by numerous studies over the past 85 years. Public health officials seemed to have clung to this distance, possibly due to pragmatic reasons.

Here is only the latest paper I could find. There is mountains of research on this.

https://www.pnas.org/content/early/2.../18/2019324117

Researchers examine which approaches are most effective at reducing COVID-19 spread

Summary: Researchers have found that physical distancing is universally effective at reducing the spread of COVID-19, while social bubbles and masks are more situation-dependent. The researchers developed a model to test the effectiveness of measures such as physical distancing, masks or social bubbles when used in various settings.

This is why physical distancing is seen as the first line of defence against transmission. Other initiatives such as mask wearing are definitely secondary in their effectiveness.

[valhalla360]

Originally Posted by NPCampbell

I'm not sure that it can be said that a majority of the viral particles hit the ground after 2 meters. The 2 meter distance is based off the Wells Curve from his associated paper written in 1934. 2m was Wells threshold for the max distance traveled by large droplets. Unfortunately it was based entirely on mathematical formulas with no empirical testing. It has been shown to be incorrect by wide margins by numerous studies over the past 85 years. Public health officials seemed to have clung to this distance, possibly due to pragmatic reasons.

The problem with the way the 6ft rule was implemented was like it was a magical number and the virus couldn't go any further.

Reality, is the further away you are the less likely for particles to reach you. So it's an odds game.

If you sneeze directed at someone 1ft from your face, pretty close to 100% chance particles hit their face and in large numbers.

If you sneeze directed at someone 50ft from your face, pretty close to 0% chance particles hit their face and if they do it's in much smaller numbers. Problem is it's completely impractical to keep people spread 50ft apart and function.

6ft is just a convenient number far enough apart to reduce transmission while still allowing some level of functionality.

A couple of key items can drastically impact the spread:
- What way do you sneeze? If you are 1ft away but turn away from the person and sneeze in the opposite direction, you drastically reduce the transmission likelihood compared to sneezing in their direction.
- Wind/airflow can drastically impact spread. If you are 6ft apart and sneeze into a 15kt wind, someone upwind is highly unlikely to get hit. On the other hand 10ft spacing and sneezing downwind towards someone, may be worse than 6ft with no wind because the wind carries it to them before it can dissipate and fall to the ground.

[valhalla360]

Originally Posted by Emouchet

Thermal camera are not so accurate. Reading body temperature accurately requires a real time calibration to a reference, and even then, accuracy is within +/-2C.

So, considering 37C is normal, and 40C is someone really sick, with a +/-2C accuracy, where do you set the limit ?


Learn-the-limits-of-elevated-body-temperature-screening:
https://www.vision-systems.com/camer...ture-screening

The problem with your logic is you are assuming you need a 100% accurate tool to be effective.

If you catch even 50% of infected passengers, you have significantly improved the situation.

Or you could use it as a first pass screening. If there is a 2 degree error rate and 40C is considered a risk, anyone over 38C gets pulled aside for a closer non-contact thermometer check. Depending on the exact shape of the error curves, that could mean 60-70% of people pass thru without stopping and you only have to take individual tests on 30-40%. This drastically reduces disruption to passengers and reduces staffing needs while achieving the same level of protection vs everyone getting stopped for a non-contact thermometer reading.