Some New Science on Virus Transmission on Airplanes

[Sand crab]

I have flown 4 times across the US in the last 5 months including 2 weeks ago. Everyone wears a mask. The first 2 times the center seat was empty but it was packed the last 2 times. No temp scanners that I saw.

[RKsailsolo]

Even if the plane atmosphere is clean, you risk infection in the airport.

[Firehoser75]

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

While a cloth mask will not PREVENT (totally) the spread of the virus, there are now many studies showing that wearing a mask (properly, and by that I mean covering your nose and mouth, not wearing it around your neck) will reduce spread by reducing the viral load present (both coming out from the "infected" person and coming into the airways of the "other" person). However, as a big part of slowing spread, people who are obviously sick (coughing, etc.) should be staying home (or at least out of the public).


I heard what I consider a good analogy the other day. None of the methodologies to slow the spread of Covid-19 are 100% effective. Even the future vaccines will not be 100%!!
Each method (masks, distancing, increased ventilation, contract tracing, quarantining, etc.) can be considered to be like "swiss cheese". They all have "holes" in their overall effectiveness (some more, some less). However, by stacking multiple layers on top of each other (by using more than one method), these holes start to close over with the holes "not lining up" and the overall effectiveness of the entire "system" of interventions improves, maybe even approaching 100% if several layers are used.
Along with ensuring that your immune system is functioning at it's best (healthy eating, Vit. C and D, lots of sleep, reduce stress, etc.), minimizing your viral load (amount of virus you are exposed to) will give the best results. Small enough load, you won't get sick, or if you do, the seriousness of your illness will likely be less than with a large load, as your body has a chance to develop defences to the small number of "invaders" before potentially being overwhelmed by an initial "large" army if you take a large viral load.
Hopefully the vaccines will be safe, effective, and well received.

[Dockhead]

Originally Posted by RKsailsolo

Even if the plane atmosphere is clean, you risk infection in the airport.

Well, you risk infection in any public place. Are you saying that airports are riskier than other public places? Do you have facts?

[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.

If you are sick and coughing you have NO BUSINESS leaving your home, mask or not.

[oleman]

Originally Posted by Dockhead

This: https://wwwnc.cdc.gov/eid/article/26/11/20-3299_article

One infected passenger in business class apparently infected almost the whole business class section, on a long haul flight to Vietnam.

The index case was symptomatic, coughing, and not wearing a mask during the flight.

I have been flying a LOT since borders reopened in May -- average couple of times a week I guess. I have not felt unsafe -- everyone is masked, and I've never seen a person with a cough on board. Planes are not full so I'm usually able to sit fairly well separated from other passengers.

This study does give one pause however. I'm kind of surprised at how far away people were infected, in the studied case. A couple of meters of separation doesn't do the trick, in the absence of masking, anyway. I had thought that the ventilation systems on planes would greatly reduce the spread of airborne viruses; guess not.

The people in charge have known since the first mass people movers that containing masses of people in a sealed box with recycled air is a recipe for airborne disease. We the public were very lucky until the latest fiasco!
Personally every long flight I have ever been on left me with some viral condition. Many times I would return home and make my whole family sick.

[mountaindweller]

Originally Posted by Dockhead

This: https://wwwnc.cdc.gov/eid/article/26/11/20-3299_article

One infected passenger in business class apparently infected almost the whole business class section, on a long haul flight to Vietnam.

The index case was symptomatic, coughing, and not wearing a mask during the flight.

I have been flying a LOT since borders reopened in May -- average couple of times a week I guess. I have not felt unsafe -- everyone is masked, and I've never seen a person with a cough on board. Planes are not full so I'm usually able to sit fairly well separated from other passengers.

This study does give one pause however. I'm kind of surprised at how far away people were infected, in the studied case. A couple of meters of separation doesn't do the trick, in the absence of masking, anyway. I had thought that the ventilation systems on planes would greatly reduce the spread of airborne viruses; guess not.

I'm a little late to this thread, but have some insights as an active airline captain for a major US carrier. First, this case study flight occurred on Mar 1, 2020 and the passenger was symptomatic and not wearing a mask. We now have a better understanding of how to mitigate possible exposure to the virus. For example, our aircraft are deep cleaned between flights, each passenger is provided a strong disinfectant wipe to further clean their space, all of our aircraft are equipped with HEPA filters that recirculated air is cycled through, temperature checks, health declarations, required Covid tests for crew and passengers to most international destinations and Hawaii, on board service modified, flight attendants monitor mask compliance (yes, anti-maskers can be a problem).
It's not fool proof, but I feel safer on the plane than I do on the packed train that connects terminals, the hotel van, or security line.
I am not convinced that traveling by air increases your risk of contracting Covid any more than being in any other public environment. I know every effort is being made to provide safe travel. Cheers and Stay Safe.

[Midnight Son]

Pressurization valves are on the bulkhead at the rear of the aircraft.

So all airflow traverses the whole cabin.
We used to like it when smoking was allowed. could spot the leaks, by the nicotine stains.

I know gross, not as gross as cleaning the valves for inspection/disassembly.

Thankfully I got full time work in the mines.
But that is another story.

[P3sailor]

All commercial aircraft are equipped with outflow valves, which allow the aircraft to maintain a comfortable cabin pressure from takeoff to landing. The location of these valves vary from aircraft to aircraft thus, when open, pressurized air exits the aircraft, passing by and exposing expelled air, from the passengers and crew, to all passengers in the cabin. This is the main reason I will not fly until this virus has passed, the exposure risk, in my opinion, is too great. Just my 2 bits worth.

[Dockhead]

Originally Posted by mountaindweller

I'm a little late to this thread, but have some insights as an active airline captain for a major US carrier. . . .
It's not fool proof, but I feel safer on the plane than I do on the packed train that connects terminals, the hotel van, or security line.
I am not convinced that traveling by air increases your risk of contracting Covid any more than being in any other public environment. I know every effort is being made to provide safe travel. Cheers and Stay Safe.

Thank you for your service in the noble task of making it possible for people to travel long distances in reasonable periods of time. I for one am grateful, and it's an incredibly tough time for the air transport industry.


Everything I have managed to learn backs up what you say. Rationally or not, I don't feel unsafe on planes at all, and I'm taking international flights a couple of times a week. I feel much less safe in the security line etc. All the airlines I've flown on are taking it incredibly seriously and seem to have very well thought out set of measures to make flying safe. I'm really glad for that.

[NedX]

Originally Posted by mountaindweller

I'm a little late to this thread, but have some insights as an active airline captain for a major US carrier. First, this case study flight occurred on Mar 1, 2020 and the passenger was symptomatic and not wearing a mask. We now have a better understanding of how to mitigate possible exposure to the virus. For example, our aircraft are deep cleaned between flights, each passenger is provided a strong disinfectant wipe to further clean their space, all of our aircraft are equipped with HEPA filters that recirculated air is cycled through, temperature checks, health declarations, required Covid tests for crew and passengers to most international destinations and Hawaii, on board service modified, flight attendants monitor mask compliance (yes, anti-maskers can be a problem).
It's not fool proof, but I feel safer on the plane than I do on the packed train that connects terminals, the hotel van, or security line.
I am not convinced that traveling by air increases your risk of contracting Covid any more than being in any other public environment. I know every effort is being made to provide safe travel. Cheers and Stay Safe.

Thanks, Captain. I definitely appreciate your comments. And I am seconding Dockhead's appreciation for what you do.

Do you happen to know the minimum size of particles for which that filtration system is effective? e.g. 10 microns, 5 microns, < 5 microns? A few months ago, when people thought SARS-CoV-2 was transmitted when relatively large droplets got in your eyes, nose, or mouth, a lot of modern systems, which are effective for particles as small as 5-10 microns, were considered safe.

Given what we know now about aerosol spread of SARS-CoV-2, really effective filtration is something that can handle SARS-CoV-2 particles that can be as small as 1 micron.

Of course, if passengers didn't take off their masks to eat, and people didn't sit close to each other, what you have in place would be enough. But I don't think that happens on a transcontinental flight...

[RKsailsolo]

Originally Posted by Dockhead

Well, you risk infection in any public place. Are you saying that airports are riskier than other public places? Do you have facts?

Yes. Any public place with people and especially indoors presents infection risk. Facts? Do you hear Dr Fauci and others warnings? I make the distinction on airports only because you must pass through them to get on the flight.

[Dockhead]

Originally Posted by RKsailsolo

Yes. Any public place with people and especially indoors presents infection risk. Facts? Do you hear Dr Fauci and others warnings? I make the distinction on airports only because you must pass through them to get on the flight.

OK, so you're NOT saying airports are riskier than other public places.


I think how dangerous any public place is a function of how crowded it is, wouldn't you agree? If we had big crowds in airports, people packed into long lines for security control, etc., then yes -- I agree this would be quite dangerous.


As it is, the airports are NOT crowded now. People keep a good distance away from each other, everyone is wearing masks, personnel wear gloves, a lot of cleaning is going on continuously, hand wash stations everywhere -- I think under these conditions, airports are among the safest public places to be. At least the airports I have been flying through.

[Dockhead]

Originally Posted by NedX

. . . Do you happen to know the minimum size of particles for which that filtration system is effective? e.g. 10 microns, 5 microns, < 5 microns? A few months ago, when people thought SARS-CoV-2 was transmitted when relatively large droplets got in your eyes, nose, or mouth, a lot of modern systems, which are effective for particles as small as 5-10 microns, were considered safe.

Given what we know now about aerosol spread of SARS-CoV-2, really effective filtration is something that can handle SARS-CoV-2 particles that can be as small as 1 micron.

I believe HEPA filters, in order to be called HEPA filters, have to filter down to 0.3 microns.


See: https://en.wikipedia.org/wiki/HEPA

[Singularity]

Travel by airline is just not sitting in a seat; the entire constellation of exposures 'door to door' must be considered (assuming avoiding illness is the concern, and not just illness obtained on an airplane is the concern).
-------------------------------------------
A survey of 700 epidemiologists:
https://www.nytimes.com/2020/12/04/u...s-survey-.html

Review Article: Influenza Transmission on Aircraft
...overall secondary attack rate among traced passengers of 7.5%. Of these secondary cases, 68 (42%) were seated within two rows of the index case.

Behaviors, movements, and transmission of droplet-mediated respiratory diseases during transcontinental airline flights

For the infectious passengers, we use the conservatively high transmission rate of 0.018 per minute of contact, which is four times the transmission rate we estimate (16), which describes an incident in 1977 in which 38 of 54 passengers and crew became infected with influenza-like illness after waiting in an airplane on an airport tarmac for 4.5 h with no air circulation.

Behaviors, movements, and transmission of droplet-mediated respiratory diseases during transcontinental airline flights

40% of the transmission occurred outside of the two-row zone, suggesting that movement may be an important factor in disease transmission

Transmission of infectious diseases during commercial air travel

One 3-hour flight carrying 120 passengers travelling from Hong Kong to Beijing on March 15, 2003,31 began a superspreading event accounting for 22 of the 37 people who contracted SARS after air travel.