Bjorn’s Corner: Do I get COVID in airline cabins? Part 5.

By Bjorn Fehrm

June 5, 2020, ©. Leeham News: In our Corner series about flying during the COVID-19 pandemic, we dig deeper into how the virus spreads.

In the last Corner, I wrote, “Recent research points to SARS-CoV-2 spreading over droplets rather than aerosols.” I later modified it to “spreading more over droplets than aerosols.”

Let’s dig into what I tried to say and why I changed the sentence.

Figure 1. The spreading of droplets when coughing.

What do we know about how COVID-19 spreads?

Recent podcasts with Professor Drosten and other reports deal with what we know about how COVID-19 spreads. We now have millions of infected people and five months of observations to fall back on.

The researchers try to understand what characterizes so-called superspreading events, where few infect many. If we can avoid these, we can control the pandemic with targeted actions rather than general lockdowns.

A few facts stand out from the studies:

  • The examples of superspreading events are from nursing homes, sports event or ski resort bars/cafes, churches, restaurants, hospitals, cruise ships, meatpacking plants, prisons. What do they all have in common?
  • These spreading events are all indoors, with poorly ventilated environments (= low air movement and high relative humidity, some with low-temperature air) and with concentrations of people.
  • Many of these involve intense vocal activity (loud cheering/chanting in a football bar/music concert, singing in a choir, talking with a loud voice because of a noisy environment, etc.).
  • Zumba classes leading to intense breathing causes spreading, whereas Pilatus classes don’t (Pilatus is a slow introspective practice).
  • In a study in China analyzing 318 superspreading events causing infection clusters, only one was outdoors.

Further observations:

  • For home infections, they are twice as common between spouses as between parent and child. Why? Because spouses sleep in the same confined room during the night, whereas kids are met during late afternoon/evening and then for a short duration in the morning.
  • The period when a person is SARS-CoV-2 infectious is short. Unfortunately, the most infectious period is one to two days before you know you have COVID-19, if you ever know it (half of us don’t). When you have symptoms and stay at home, you no longer spread the virus; it’s too late. This explains why SARS-CoV-2 spreads so fast. The bulk of the spreading happening before symptoms is different from previous epidemics like SARS and MERS.
Conclusions from the research

There are several insights from the research. High risk of transmission of COVID-19 occurs when;

  • The environment has a calm air, ideally with high humidity and low temperature. This helps the virus survive in the smaller droplets/aerosols that stay in the air longer.
  • The environment causes people to use their vocal organs more actively. Coughing and sneezing are evident virus spreaders (Figure 1). We now have to add any activity generating strong lung-air pressure waves to this, like shouting, chanting, loud voice communication, or singing.
  • These throat pressure waves generate and eject droplets/aerosols, and these droplets/aerosols are then inhaled by the person you talk to. Many times the person is also leaning/turning his face toward you if the environment is noisy. If your nasal or lung tracts have the virus you can infect others.
  • In calm and normal to high humidity air, an aerosol cloud hovers for longer and the viruses avoid drying out. Outdoors, where it’s windier and dryer, the droplets/aerosol disperses and dries out.

So what do we conclude regarding air travel from these insights?

  1. Wear a face mask. All these cases feature droplets/aerosols carried by the pressure waves from the person’s lungs, down to normal talking waves. A face mask dampens the pressure waves so the spread radius reduces and it catches droplets and aerosol content.
  2. Stay in confined, non-ventilated spaces like the air bridges or transit buses for the minimum of time and don’t stand face to face with people. Keep your distance.
  3. When in the cabin, the boarding and deboarding are the dangerous parts. Travel with airlines that prescribe masks and have thought out procedures for boarding and deboarding. Keep distance and don’t face people for long. And stay calm, let it take time. Airlines shall have the ECS (the cabin airflow) on maximum speed during boarding and deboarding.
  4. Once seated during the flight, you are now in a more virus hostile environment than outdoors in the above examples. The airspeed is around 1m/s downwards, and the air humidity is about half of the outdoor air humidity. Evidence point to this being the low-risk part of the trip. Any virus loads passing an infectious person’s masks have a tough time surviving and reaching another passenger’s nasal cavities/lungs.

The statistics that exits support that the length of the flight doesn’t affect the risk of infection. It’s the phases around the actual flight that contains risks. A visit to the bar in the departure hall is probably riskier than the flight itself (unless it has an outdoor terrace).

35 Comments on “Bjorn’s Corner: Do I get COVID in airline cabins? Part 5.

  1. will you address the question of cabin seating? are these to be modified from the before bug seating age- or do you recommend that they be?

    have new regulations governing passenger behaviour been issued by any one of the authorities involved?

    what about airport workers? any new regulations issued here?

    have any airlines issued any rules and regulations?

    do you believe there is enough space in airports especially at check in, security checkpoints etc to keep distance as recommended

    are body searches to be allowed?

    how is passenger identification to be achieved if masks must be worn at all times

    are all pax possessions to be cleansed at any point, passenger personal possessions, bags, suitcases etc?

    have recommendations be made by authorities or airlines as to the extra time the passenger should program for processing for flight?

    • Hi Gerrard,

      here is what I know:

      will you address the question of cabin seating? are these to be modified from the before bug seating age- or do you recommend that they be?
      The issue of leaving a seat free is focusing a costly effort for the airlines on the low risk part of the trip, with questionable gain. I’d rather they spend their money on free masks of high quality (and give the passenger two so he can keep one for personal use, it costs so little extra but will be remembered) and improvements to the high-risk events such as boarding/deboarding so that no confined still stands occur.

      have new regulations governing passenger behaviour been issued by any one of the authorities involved?
      Most, if not all European and Asian jurisdictions require the passengers to wear masks at the airport and during the flight. For the Americas, it varies AFAIK.

      what about airport workers? any new regulations issued here?
      For those in passenger contact, rules of mask-wearing, distancing, and conduct at check-in counters etc.

      have any airlines issued any rules and regulations?
      Same as above, EU and Asia have rules including mandatory masks. For the Americas, it varies AFAIK.

      do you believe there is enough space in airports especially at check in, security checkpoints etc to keep distance as recommended
      Masks are more important than distancing, with them always on it should work, especially as with the passenger numbers we have, there is the place, at least for the next future.

      are body searches to be allowed?
      As normal, in security control only.

      how is passenger identification to be achieved if masks must be worn at all times
      You can take the mask off for ID purposes in assigned places with distancing rules. It then poses no extra risk.

      are all pax possessions to be cleansed at any point, passenger personal possessions, bags, suitcases etc?
      Not to my knowledge.

      have recommendations be made by authorities or airlines as to the extra time the passenger should program for processing for flight?
      There are recommendations for the extra time made by the airlines, check their webs.

      • Dear Bjorn

        Thank you for your careful responses

        In essence nothing is going to change except an attempt to enforce mask wearing, and by definition the wearing of a mask is a social order activity, rather than a medical or health order

        The Asians were masks not because they worry about vapour etc, is is because their social structure requires the maintenance of non expressive impassive expression at all times

        Wearing a mask re inforces this non expressiveness, and of course has an incidental bug advantage

        Western society has always placed great importance on the face being expressive, and communicative of character emotion and intention

        By the same token Asians do not shake hands, which for Westerners is an importance peace offering

        To suddenly disrupt such ancient habits is not only difficult but dangerous – who knows what wild ideas will lurk behind the Mask?

        • That’s a new one ‘asian-splaining’… I’m incredulous but not surprised in a way.

          • @DofU
            An Asian would comment not giggle

            My comment was the difference between Asians and Westerners

            I can not suppose that to do so is un allowed

            Do you have anything to comment?

          • Save your comments about what you do know and leave ‘explaining’ what other cultures may or may not do to them. It wasnt just a phrase it went the full 9 yards.
            A lot of your comments here are like that, uninformed opinion, thus the no surprise.

          • @dukeofurl

            You appear to be someone who can make assumptions about race/culture yet who will allow comments about any race/culture only to members you suppose to be of such

            This is ignorance celebrating stupidity

        • > The Asians were masks not because they worry about vapour etc, is is because their social structure requires the maintenance of non expressive impassive expression at all times

          Wearing a mask re inforces this non expressiveness, and of course has an incidental bug advantage

          Western society has always placed great importance on the face being expressive, and communicative of character emotion and intention

          By the same token Asians do not shake hands, which for Westerners is an importance peace offering

          Asian here. This is ALL BS.

          • @phoenix

            You claim to be Asian, and you claim this allows you unique authority to dismiss with an insult the comments of someone of who’s place of birth or skin colour or race you are ignorant

            Yet you give no information nor comment – is an insult a substitute for such?

      • Dear Rob

        ‘Guidelines’ are not going to ‘do’ much by way of instituting or enforcing a new régime, except protect the backs of a few international bureaucrats ‘We told you so’

        ICAO is toothless, if it is possible to be more toothless than the WHO, it’s the ICAO

        Is no one to issue regulations or laws?

        If not then then economics are going to dictate institutional and corporate response – airlines will ask you to wear a mask, full stop, no modification of sitting arrangements, except perhaps in first class where social distancing is the norm in any case

        If an airplane full of let’s say ‘protesters’ à la Floyd marchers – for which demonstrations it seems absurd or impractical to expect or to enforce distancing and masks (other than gas masks) – should not/refuse to wear masks, the pilot is going to disembark the plane and cancel the flight?

        No airport re design? etc etc? So in which case, effectively nothing will be done to back up/prolong the elaborate regulations supposedly so necessary to ‘save’ lives

        It is important to remember the social contract – while the people were panicked by threats of a plague they cowered and obeyed ‘regulations’, once discovering they have been lied to – they will not

        Those of you who wish to conform to the new order and protect yourselves, fly first class, use VIP lounges, accelerated and distanced Gold Club service in the airport, and everywhere else

        • Gerrard, I think this is a mostly negative view. We’ll have to see the level of compliance that occurs. The articles I’ve read on airline and airport plans seem to be reasonably aligned with the guidelines, as are the things Bjorn is telling us.

          Most of the outlined measures are thought of as being temporary, but I suspect if they improve service overall, they will become permanent. At this point we don’t know how much of air travel will go back to normal, so the extent and permanency will need to develop as we go.

          • Dear Rob

            My comment is not negative – it points out that no authority has yet taken any initiative to issue rules and regulations

            But has left whatever new measures may be taken to the discretion of airlines or airports

            ‘Compliance’ you say, compliance with what? With Airline to airline, airport to airport, country to country temporary measures, which will vary?

            What are the outlined measures plural you mention – the only one I can see is the wearing of a mask everywhere, keeping some distance in temporarily uncrowded airports but which will be impossible if traffic comes back to near ‘normal’ – perhaps you’d like to list the other measures, US then by country

            Will anyone in an administrative fashion be tasked with tracking the variation of measures worldwide, measure compliance rates, find improvements?

            You are looking at ICAO to do this ?- you seem to vest authority in ICAO guidelines which is largely un present in most of the rest of the non US world- but if not an global administrative authority then who?

            The market it seems will measure what will work

          • Gerrard, if you read the guidelines and some of the airline plans, they list health check at TSA, extensive and repetitive cleaning of facilities and during flight, distancing at all phases, isolation of ill or uncooperative passengers, distribution of sanitary kit to passengers, air handling and ventilation requirements, PPE for crew and staff, electronic boarding passes, new limits on carry-on, baggage assistance/delivery, etc. There’s quite a lot to it, it’s not just lip service.

            As far as regulations, I suspect those will follow after we know better what is effective and practical. The FAA generally allows a period of comment and input before ruling. The COVID situation is pretty new so it will evolve as we go.

          • Dear Rob

            My point is that these are merely guidelines, so subject to mutation and variation, and no authority has dared to impose strict regulations

            Why is this ? Because, apart from washing hands, or cleaning an airplane better, and the other at the margins measures you mention, no gvmt is going to obligate social distance passenger seating, nor rebuild airports to accommodate social distancing

            I do not think that you believe any gvmt will

            Yet it is social d which up to now is/was considered necessary and essential

            All measures will be left to market – gvmt will abandon responsibility to ‘guidelines’ – how seriously does anyone take guidelines which are un enforceable and, as you say, temporary

            The existing social contract was broken by lockdown, who how and when is a new one to be built, much less enforced

          • While Gerrard is being blunt, there is also massive truth there. Realistic vs pie in the sky.

            Realistically guidelines are a bunch of nonsense.

            Lets look at Costco. Pretty proactive in its operation and handling of the issues.

            They had a seniors time slot. Outside was anything goes (and did) per the lines (on their property)

            Inside? First they they do is get in your face and want to see your Drivers License ! Ok, so a 59 year old slips in, so what ?

            End of the world of course. Lets expose every older person going to Costco so they can see ID . That checker of ID is a superior spreader mechanism as they see ALL Seniors and expose ALL senor to that point of contact. Wonderful.

            So, both you and the Costco employee have a very close face to face to prevent that heinous crime.

            So yes, sans the vaccine laws and regs and enforcement of same.

            Leaving it up to corporations simply has the Costco variations or worse.

            Bottom line its not going to work and the only real fix is vaccine (or regulations)

            Bottom line while Bjorns information is extremely good overall, sans a vaccine it does not matter even if you are safe on the plane.

            Bluntly the guidance is called lip service and is nothing more than spent air.

          • TW, Costco was actually ranked highly for compliance with coronavirus safety recommendations and guidelines. This was based on market & customer research, as well as numerous store visits.

            https://www.foxbusiness.com/lifestyle/trader-joes-costco-whole-foods-coronavirus-safest-Ipsos

            Your assessment is typically negative, but I think not representative of what most people think or do. You tend to ridicule optimism, but I would point out that most people are not going to accept defeat and do nothing. They’re going to find ways to get on with their lives. And they will be encouraged by progress and success.

            If you want to say that none of these things have value and can’t possibly work, that’s fine, you can stay home as long as you wish.

            But please realize others won’t share your pessimism, and will work toward improvement and returning to normal as much as they can. They are not wrong for doing that, or for disagreeing with you.

            You’re old enough to remember an animated TV show “Gulliver’s Travels”, with an iconic negative character named “Glum”. That’s who I think of when I read some of your posts. The world is not all doom and gloom, some things do actually work. We can’t know which ones unless we try.

  2. You mention low temperature air indoors. The only way to get low temp air is running it through an Air Conditioning unit (coil, tending to a Refrigerant Gas (R-134 etc) but can be Chilled Water coils from central system).

    In either case the Coil pulls moisture out of the air as it condenses on the cool surface.

    Mostly you do not have high humidity with cooled air system.

    • The low temperature was with reference to the meatpacking problems, not homes. An air-conditioned home would be a hostile environment for the virus because of low relative humidity.

      • Got it, thank you. Meatpacking low temp and low humidity would make the low low humidity assist of no value by the nature of the close proximity issues.

        To close and the Virus load transfer regardless (sans a massive UV light flash with each breath)

  3. I think Relative Humidity (RH), Temperature, UV light (different wavelengths), the ionization of the air (Negative / Positive), air movement, air density etc. would be great to measure and control in terms of the virus exposure. There is limited data available. One study on RH and Temp a few years ago, suggested that high RH and high Temperature help kill the virus. To really kill the virus, you need temperatures hotter than humans could tolerate for long periods, but, some car makers are modifying their vehicles to do this.

    Temp & Humidity on a virus (surfaces, not humans)
    ==============
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2863430/
    =================

    Ford using hot temperatures to disinfect Police cars between shifts. (maybe the same can be done with Aircraft overnight or between long gate waits?)
    ==================
    https://www.detroitnews.com/story/business/autos/ford/2020/05/27/ford-police-interceptor-vehicles-can-now-turn-up-heat-on-coronavirus/5263758002/
    =======================

    • Richard:

      Low humidity is not a solution, its a factor that can help.

      Sans massive doses of bleach and UV of Mercury proportions, people in a group are an issue.

      You can assist around the edges but the issue is still people the virus and proximity .

  4. I truly do not understand why FAA does not mandate that all passenger aircraft install ultraviolent and air ionizers (e.g. Reem’s Halo) in the filter system which kills viruses, mold, alergens, etc. as the air passes through the recirc system. We have had one in the house for years. It works great. the technology is not new, but airlines are too cheap to purchase, install, and maintain them.

  5. Hi Bjorn,

    I understand you have a background as an Aeronautical engineer and have a vested interest in the aviation sector, so it would be quite a surprise if your conclusion was that during this pandemic it’s not safe to fly.

    You are well aware that the FAA has not set rules for preventing the spread of infectious diseases in airplane cabins.

    I’m sure you are familiar with Qingyan Chen, a Purdue University engineering professor who lead a major FAA-funded research project on disease transmission aboard aircraft and has received research funding from Boeing. This was research was done after the SARS pandemic.

    Professor Chen has studied air quality in planes and has concluded that while planes get high marks on some measures, many of the industry claims are misleading.

    According to Professor Chen: “airplanes are not designed to prevent infectious-disease transmission.”

    You are also of course familiar with the China Air flight from Hong Kong to Beijing in which, thanks to just one infected passenger, 22 passenger were diagnosed with confirmed or probable cases of SARS, 5 of which died.

    Working with two Boeing engineers and a team of researchers from Purdue, Professor Chen studied how an airplane’s ventilation system affects the risk of contracting SARS, very similar to Covid-19.

    He found that passengers sitting with a SARS patient in a seven-row section of a Boeing 767 would have a 1-in-3 chance of getting sick from a five-hour flight. On a shorter 737 flight, the risk was 1 in 5.

    So it seems flying is safe, as long no one aboard is infected.

  6. Dear Rob

    You are despairing about nothing – mere rhetoric

    Not to have faith in gvmt cowardice to fail to impose regulations yesterday said to be essential to survival is to be positive about the freedom to chose how to order society either as individuals or as community

    This is not to accept defeat – you are being dramatic along the lines of the Imperial College gotta do this else millions will die

    You seem to suppose that ICAO guidelines or Airlines market driven choices reflect a kind of expert/commercial/industry consensus which should be respected and which should give we the people hope for a safer future, else we have nothing

    You think the FAA will pronounce? Self certification is the FAA mantra – to self certify is fine for you the people, not fine for a regulatory authority – disastrous if you are Boeing

    No one is saying that washing your hands ‘has no value’, nor that cleaning a plane better is not ‘better’, these super technical measures are merely common sense masking up

    What the people are saying, à la Floyd, is that there are higher priorities than bending the knee to the bug

    ‘I’ll bend my own knee my way’ because the gvmt has given up on police regulation as on bug regulation, as on…. –

    Actually that’s a positive, not a negative, given just how badly the gvmt (and FAA, and the ‘experts’ and the CDC and….and) have got bug everything wrong so far, made every mistake there was to make, now only cease to rule and regulate because they are fresh out of mistakes

    If indeed ‘some things work’ as you say, then some things do not- the some things of this (and recent) governments

    You are inverting reality by throwing the government at me, guidelines and all, as if this was the people’s choice and inevitable destiny, when in fact the people, watch tv, are voting with their feet, preferring their own risk assessment and risk management

    • Gerrard, your views are driven by political leanings and that’s fine. The government has a role to play in all of this, no doubt. I was speaking more to the world view that progress and improvements are possible, so efforts in that direction shouldn’t be dismissed out of hand.

      The protests regarding George Floyd and general police behavior have been a long time coming, and have my support. There are signs that the militarization of civilian police will finally come under scrutiny. Even Republicans have now introduced legislation to reduce the 1033 program which transfers military hardware and training to the police. That was meant to fight the drug war and provide homeland security, but has mostly been used against citizens for crowd control.

      There is a balance & battle between the legislative branch which writes the laws, and the executive branch which enforces them. The executive branch tries to enhance and maintain its power, the legislative branch reigns them in. That has always been true, but we are seeing some particularly egregious examples of executive power right now.

      In the past, those powers have also been used for good. The military has been mobilized to protect protesters and maintain people’s rights as well. So we have to seek balance and not just react to the politics of the moment. Most police are good and want to do the right thing, just as most protesters are not vandals or looters. There needs to be recognition that the goal of these two groups is the same, a just and fair and safe society for all. It’s an elusive goal and our implementation of it is very far from perfect, but we pursue it nonetheless.

      Since this is an aviation blog, I’ll stop there and suggest you do the same. We cannot resolve political problems or differences here. Best to focus on the topic at hand and contribute to the discussion and solutions as we may. I appreciate your posts and TW’s as well.

      • Dear Rob

        No one is indifferent to technical progress – every crisis serves to stimulate these

        The debate is as to governance and/or implementation and regulation of such

        These are obviously concerns of society at large – as in the many debates about the Max failure

        I am not sure where you obtain the notion that it is possible to ‘dismiss out of hand’ technical advances – to criticise the FAA in connection with the Max certification or the CDC ditto bug is to find fault not with technology but with bureaucracy, and in a larger sense with consent

        No one would reject per se the measures put forward in this post by Bjorn

        But one may say that everyone would seek to understand the parameters of the possible, which includes technically possible, within the context of culture society and common assent

        Lockdown, martial law, and 6 feet distancing, exist as social/political measures which may be imposed or maintained by force, these are not ‘technical’ solutions, and to argue that such constraints may be adopted, obtained or operated by common consent is redundant

        Bjorn wisely kept clear, as far as he could keep clear, of such measures, I was pointing out that it looks like everyone else, apart from one or two pockets of resistance, is likewise keeping their distance from them

        • Gerrard, to remain on topic, I’ll just say that air travel is likely to resume, and doing so will involve changes in procedures that are deemed technically effective in reducing the spread of COVID. I don’t claim any special knowledge as to what those are, or should be.

          But obviously people will be trying to understand this and figure it out, as Bjorn is doing here. I’m willing to listen to all of what’s learned or proposed, so as to understand and evaluate, without predisposition that it can’t or won’t work. There will be many views and ideas, some of which won’t be implemented, but that’s all part of the process.

          That’s all I’m saying, and will leave it at that.

          • Dear Rob

            The process is as follows-

            To seperate out what is technically possible in aviation, what is the cost of such, and what may be, by consent and by administrative procedure, certification or regulation, authorised or required

            Even so there may be some measures which escape such purview, adopted for commercial reasons by airlines or airports

            Beyond that there are associated social/political ordained measures which may only be considered in an overall context, and which can not be limited to aviation

  7. If you are afraid to travel in an airplane please do not fly.

    • Well I am concerned at whats at either end and will not fly.

      Bjorn has solid support that the aircraft may be ok, but missing as well is the viral load an adjacent passenger is emitting.

      So, lets call their mouth to my mouth at a distance of 17 inches. Call its a 2 hour flight.

      The viral load you pickup? Huge, 10 minutes is considered what is needed.

      And more and more its clear that many people who are emitting do not know they are sick yet. Fact is that the prime emitting period is non symptom period.

      So, maybe, at 34 inches (empty middle seat) odds are better.

      Nope, not flying.

      What I am learning is how to deal better with the Covd in day to day life and what areas are the highest risk and what are lower (wash the food and or container and then your hands and you are probably good).

      Don’t talk face to face with anyone closer than at least 3 feet and preferably 5 to 6.

      Don’t talk to anyone who is not wearing a mask (and you should too of course). A mask is a help for you, yours is a help (possibly) for someone else.

      Anyone not wearing a mask does not care about you.

  8. @Gerrard
    > You claim to be Asian, and you claim this allows you unique authority to dismiss with an insult the comments of someone of who’s place of birth or skin colour or race you are ignorant

    > Yet you give no information nor comment – is an insult a substitute for such?

    Oh please. Don’t even pretend to be not insulting while putting an insult into my mouth.

    This is also the literal definition of prejudice.

    • @phoenix

      You use the word BS, not me

      I do not insult you, I suggest you can not assume to know the race and colour of commentors

      Your claim to be Asian is merely a claim, but can not be taken at face value

      Apart from that claim and that insult you say nothing – from which one may conclude that you have nothing to say

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