.
Why Airline CEO's are obsessing about Aircraft Pure Air
Misleading HEPA-Filter Efficiency Claims?
by Bearnairdine Beaumont - June 2020
Summary
The recirculated air on-board aircraft accounts for approximately 50% of the air supply and can contain high concentrations of bacteria, dust, viruses and other microorganisms. The remaining 50% of the cabin air is provided by the engine “bleed air”. This air can contain fumes that contain volatile organic compounds (VOCs) which can create by chemical reaction an unpleasant smell, referred to by the airline industry as “odour”. This “odour” however, can signal the presence of highly toxic substances, including carbon monoxide fumes.
Despite all the promises given in marketing videos launched by many airlines in the past weeks telling the public that the air is as clean as in an OR or hospital: it is not! Any number of viral load can be brought on board by any (asymptomatic) person, who will not be detected by any fever measuring or other health check, and there is no guarantee that there would be no health hazardous fume emissions entering the cabin breathing air at any given time.
Airlines claim that aircraft cabin air quality is comparable to hospitals’ operating rooms “cleanroom” air quality.
Apparently the airline industry considers demands for a free middle seat because of Corona to be excessive. There is "a very low risk of virus transmission on board", they state, and „the majority of commercial aircraft are equipped with highly effective particle filters"; however, they do not offer any information which aircraft exactly are fitted with filters, nor what these filters filter. They simply keep repeating, that “these highly efficient filters“ clean the cabin air in such a way that it is "comparable with the sterile environment in a hospital operating room"1)
They point out that their filters have a 99.999% filtering efficiency of bacteria, fungi and viruses, and make it sound like that there is no danger of infection.(Pall)
After a little digging one finds that testing was performed on only two bacteria types – both of which are larger in size than a 0.3micron HEPA filter opening. On the Pall Aerospace website we can read that there is a 99.999% removal when challenged with the „Brevundimonas diminuta“ which is a bacteria commonly used as a test organism for validation of sterilizing-grade membrane filters due to the small size of the bacterium; they mention the „Bacillus subtilis“ which is considered a benign organism as it does not possess traits that cause disease, and the “MS2 Coliphage” virus which is generally applied as a surrogate for pathogenic respiratory viruses, such as influenza, as it is safe for personnel to handle and requires less time and labor to measure virus infectivity.
But the MS2 coliphage which is about 27 nm in diameter was not determined to be a sufficient surrogate for influenza A virus with respect to droplet persistence when applied to the N95 FFR as a droplet.
Virions, or “particles”, of coronary viruses are spherical particles between 0.06 micron and 0.14 micron in diameter, averaging about 0.125 micron, measured by electron microscope (Zhu et al, 2020). This means that coronavirus particles are smaller than PM2.5, but larger than some dust and gas particles. 7)
So, we know that the majority of viruses are typically less than 0.3microns. Testing was performed on only one virus. How was a 99.99% removal efficiency result achieved? How can virus and bacteria removal efficiency be identical considering there is a substantial size difference between them?
Laboratory-generated virus aerosols are commonly produced from liquid suspensions using pneumatic nebulizers such as Collison nebulizers, as the wet-dispersion technique simulates many dispersion processes of viruses in the natural environment The composition of liquid suspensions from which virus aerosols are generated (also known as nebulizer suspensions) is known to affect the infectivity/survival of airborne viruses . Given that many laboratory studies use artificial nebulizer suspensions (e.g., cell culture media) that do not mimic natural release of virus aerosols from body secretions (e.g., human saliva), it may be assumed that the survival of airborne viruses determined in laboratories most likely do not represent that in real-life situations. 8)
A 2017 study by the University of Hong Kong, funded by BOEING, concluded that germicidal “transmission may occur over long distances” and take place via close proximity to infected source, airborne disbursement or fomite route 13), which could explain the excessive aircraft disinfection and cleaning taking place during this pandemic.
Clean air is odorless, colorless and tasteless.
It is rich in oxygen and feels fresh and does not contain any pollutants harmful to health. It should be neutral and thus not carry ions. In general, anything that is toxic or has electromagnetic capabilities will generate harmful positive ions – some examples: toxic carpeting and upholstery, air pollution, especially in crowded cities and industrial zones. Most studies have found that levels of positive ions are extremely high in homes, cities and office buildings 17, 18, 19. Good indoor air does not cause any symptoms typical to indoor air problems, such as tiredness, headaches, itching of the eyes or respiratory symptoms. If something smells odd when you enter an aircraft (stuffy, greasy, smokey, mouldy, gym-like stale air) where there is plenty of carpeting and upholstery it is a sign of poor-quality indoor air. Residue from bleed-air pollution and pesticide spraying sticks to the walls and seats and cannot be cleaned off by rubbing or spraying it down with disinfectant chemicals.
We need approximately 10,000 liters of clean air per day. Without clean air, we can survive for around three minutes, without clean water a maximum of three days and without food about three weeks.
Many people, passengers and aircrew alike, suffer from symptoms caused by poor indoor air on flights. Poor aircraft air quality is not only caused by germs, bugs and viruses, but chemical fume emissions including CO entering the cabin via the engines, from where the “fresh air” is drawn and pollute the air often dangerously.
Research shows that the majority of health problems are caused by particulate matter.
The indoor air quality depends first and foremost on how many people are in the room and how they behave. This influences the air turbulence in the room. It also depends on items in the room (seats, carpets, blankets, hand luggage, purses, cameras etc.). In an OR devices and tools etc. are sterilised - aircraft seats, floors and passenger’s clothes and luggage aren’t.
Trying to work with single factors ( 1 virus, 1 bacteria, 1 –electro-chemical substance) is virtually impossible, even useless, as the result of polluted air stems from a variety of particle pollutants including dust, inorganic fibres, microbes, gaseous pollutants – and in the case of aircraft cabin air pollution up to 127 different substances have been detected (EASA), i.e. formaldehyde, ammonia, carbon dioxide, carbon monoxide, organophosphates, plus benzene, n-hexane VOCs and residue from pesticides. The effect that these air pollutants have on our health depends on their quantity, the combination effect, and the level and duration of our exposure and the individual’s general health situation, since exposure resistance varies dramatically from person to person.
Aircraft air as clean as in an OR?
The same type of HEPA filters, which are being highly praised by the airline CEO’s are commonly also used to filter supply air flow in a “cleanroom” (i.e. OR). However, as mentioned it can only collect particles of 0.3 μm and larger in diameter, which renders a need for additional air decontamination technologies such as air “purifier” units in the (OR) room. The majority of nanoparticles in cleanrooms are process-related and must be effectively removed at the source. While most particles in cleanrooms can be related to human activity, ultra fine particles are also generated by electrostatic discharge19), chemical reactions such as oxidation, and gas phase nucleation. These contaminants cannot be removed with fixed HVAC interfaced HEPA filtering systems.
One can only verify the quality of indoor air by measuring it, which offers information about the quality and purity of the air in real time. As concluded in a 1998 study by Melvin W. First (Harvard School of Public Health): “Standard qualification test tell us very little about the performance of HEPA filters under realistic use conditions” and “Efficiencies observed during standard qualification tests are not necessarily the results that will be obtained in practice”.14)
Measurement and real-time monitoring of measurement results would provide a solid basis for maintenance. The purpose of measurement is to reduce uncertainty in decisions, and that way eliminate the possibility of mistakes in corrective actions.
However, there are no real time measurements made on aircraft and there are no warning sensors installed!
How efficient this type of technology actually is in individual cases depends on the conditions on site, above all, on the actual air quality during the decisive time. “In the case of OR-clean rooms the air quality is usually only comprehensively checked once - before a new or converted operating room is handed over to the user”, Dr Weiss from Klimatechnik says. “Also, on this occasion a turbulence or degree of protection measurement is carried out according to the specifications of DIN 1946-4. This means that during the measurement the room is empty: there is no personnel, no operating table and no instruments.”
The quality of the air depends on how many people are in the room and how they behave in it, which influences the air quality. The same applies to the way in which operating tables, equipment tables and lamps are positioned in the room. It remains unclear what the air quality really is during the operation, how it changes during this time - in short: how efficient the air flow is. 2)
Before entering an operating room, surgeons and nurses etc. have to have washed and changed into sterile clothing (scrubs). Why? To keep the air as free from pollutants as possible. Are aircrew and passengers wearing sterilized clothing? No.
The air is never checked in aircraft!
Apart from HEPA filters do aircraft also have air purifying ceilings installed then? No.
A HEPA filter, whether referred to as medical, commercial, industrial or state-of-the-art, is nothing more than a filter designed to capture “99.999%” particulate matter down to 0.3µm (microns). Viruses, gases and toxic chemicals are much smaller - anywhere from about 0.1µm to 0.0001µm in size.
In their review of HEPA filters, the FAA’s Medical Institute has indicated that HEPA filters are not designed to capture gases, vapors and viruses. Reports and studies by ASHRAE, the Research Council of Norway and the Clemson University have found that HEPA filter efficiency claims of 99.97% (or 99.999%) are generally based on short-term laboratory testing using artificial challenge dust such as: the sodium flame method to BS3928 or DOP testing to Mil Std 282 (15,16). That efficiency claim has little relevance to actual filter effectiveness during long-term usage under actual operating conditions.
Air “purifiers” are a whole specialized technology in themselves, especially for “clean rooms” such as operating rooms, ICU’s etc. Realistically, they need to be capable of simultaneously mitigating germicidal and chemical contaminants. All of the supply air enters the room through these units, while air flow is controlled to create positive pressure difference to outside environment. A second unit is utilized to constantly circulate and purify the air from any process and human-related contaminants.
"Through continuous online monitoring and the corresponding permanent situation-specific regulation of the air flow, we ensure that the particle and germ contamination during the decisive cut-suture time is as low as possible," summarizes Rupert Mack: "This enables us to significantly reduce the number of postoperative infections caused by airborne germs.
And even so, according to the information provided, the TAV ceilings do not provide the necessary protection against germs during operations at the operating table, despite the high energy expenditure for air transport, humidification and dehumidification as well as air temperature control. According to Professor Martin Kriegel, this is due to the fact that the flow of air in the room is disturbed by equipment and OR personnel. This causes the displacement flow in the wound area above the operating table to collapse. "There is no longer any protection against the penetration of germs and particles," says Kriegel. 3)
What makes indoor air poor?
According to a study by Sisäilmayhdistys (Finnish Indoor Air Society), most of the problems are caused by fine and ultrafine particles from outdoor air pollution that people bring with them indoors. It is difficult to determine a single cause of poor indoor air quality as it is usually caused by a combination of factors and calls for a comprehensive approach instead of trying to fix one problem at a time.
Studies have shown that even a single substance or very small concentrations of particulate impurities or their combinations may be harmful to health.
Good indoor air quality can be achieved by preventing harmful emissions and ensuring adequate ventilation. The cleaning of the ventilation system is essential for limiting pollutant emissions, as contaminants will accumulate in the ventilation ducts. In January 2020 „Report Mainz“ a German TV production, proved in their documentary „Toxic Gas in Aircraft Cabin Air - Does it make Passengers & Crews Ill?”, that the aircraft airducts are filthy and full of toxic oily grime; it is impossible to clean the many meters of winding and hidden air ducts as they can’t even be reached without taking the aircraft apart and so the additional unfiltered air contamination source is obvious.
According to a two-year study by microbiologists and engineers at Auburn University, the problem areas for germs on planes, when not cleaned properly, are airline seat upholstery, tray tables, armrests, seatback pockets and the lavatory handles. The study found that bacteria can live for up to a week on such surfaces. In a deep cleaning, the ceiling, walls and overhead bins are sanitized, floor and cloth seats shampooed, and synthetic seat covers disinfected. There currently is no single industry standard for deep cleaning. In the past, there could be a lapse of as much as 90 days between such cleanings. Traditionally, the Federal Aviation Administration (FAA) does not regulate or inspect aircraft cleaning, leaving frequency and thoroughness up to individual airlines.
In conclusion:
The recirculated air on-board aircraft, which accounts for approximately 50% of the air supply, can contain high concentrations of dust, skin flakes, viruses, and other microorganisms whilst common occurrences like coughing and sneezing, combined with ultra-low humidity can promote the spread of bacteria and viruses and increases the risk of static electricity causing damage to equipment and additional discomfort to people.
The remaining 50% of the cabin air is provided by the engine bleed air. This air can contain volatile organic compounds (VOCs) as a result from pyrolised engine oils that create unpleasant smells. However, such “smells” are not always harmless but more often than not, toxic, causing acute symptoms such as light headedness, headaches, nausea and dizziness, to name a few, and indeed can become long-term harmful to our health.
Despite all the pretty promises and colorful, music underlined marketing videos launched by many airlines in the past weeks, with a pleasant voice telling us that the air is as clean as in an OR, or hospital: it is not! Any number of viral load can be brought on board by any (asymptomatic) person, who will not be detected by simple fever measuring or other quick health checks.
If the virus and ensuing illness are as dangerous as is said, we highly suggest that you wear a high grade mask, at minimum an FFP2 (N95) or FFP3 (N99) and best one with a valve. For additional protection a small travel air purifier which emits healthy negative ions to hang around your neck might also be a good idea, and finally: keep the air vents above your seats closed.
A statement like this one: "The health and safety of passengers, crews and employees have the highest priority for us (the airlines)" – “… appears cynical against this background and remains purely lip service” , as stated by in a recent interview by Professor Dieter Scholz from the Hamburg University of Applied Sciences’ Department of Automotive & Aeronautical Engineering 12).
Acknowledment:
I would like to thank Rein André Roos / PhD-Ing. and Reinhard Schuetz /Eng. for supporting me and providing me with assistance, advice and technical feedback.
Note:
Short excerpts and quotes from other authors have been used under the’ fair use policy’ for educational purposes. All rights © reserved to the respective authors as listed.
Trusted Research Sources
1) https://www.airliners.de/a4e-mittelsitz-corona/55314?fbclid=IwAR3lqWCQrJi7YwaJN1gMkenBBfV1oFJYGmLpm7QcFdJhpvmC8ZfDZrlqv_Y
2): https://www.management-krankenhaus.de/topstories/hygiene/konstantes-online-monitoring-der-luftqualitaet-im-op
3) https://mail.google.com/mail/#inbox?compose=CllgCJfrLftMvhMXXKbbGbLXQbQjpXGlDfxvrhnLjnrmrDDMvWdgPjWQJGcZllsMgjGtZMnwhqB and https://www.tab.de/artikel/tab_Belueftung_in_OP-Raeumen_2864301.html
4) https://pubmed.ncbi.nlm.nih.gov/11977409/
5) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4615560/
6) https://aem.asm.org/content/77/1/229
7/8) https://aem.asm.org/content/80/9/2796
9)https://www.tandfonline.com/doi/full/10.1080/02786826.2012.754841
10)http://medicalsystems.sanova.at/download/laminarairflowmobil/toulpostop.pdf
12) https://youtu.be/HdvprC-knhY / https://purl.org/corona/pr2020-06-05
13) https://onlinelibrary.wiley.com/doi/epdf/10.1111/ina.12445
14) https://journals.sagepub.com/doi/pdf/10.1177/109135059800300111
15) https://www.sciencedirect.com/science/article/abs/pii/S0032591016303849
16) https://www.ashrae.org/File%20Library/Technical%20Resources/Technical%20FAQs/TC-02.04-FAQ-68.pdf
17) IONS https://www.britannica.com/science/ion-physics
18) IONS https://www.britannica.com/science/nervous-system/The-ionic-basis-of-electrical-signals#ref606353
19) http://www.appstate.edu/~clementsjs/journalarticles/glor.pdf
20) BleedAir https://krex.k-state.edu/dspace/bitstream/handle/2097/19022/JakeRoth2015.pdf?sequence=4
by Bearnairdine Beaumont - June 2020
Summary
The recirculated air on-board aircraft accounts for approximately 50% of the air supply and can contain high concentrations of bacteria, dust, viruses and other microorganisms. The remaining 50% of the cabin air is provided by the engine “bleed air”. This air can contain fumes that contain volatile organic compounds (VOCs) which can create by chemical reaction an unpleasant smell, referred to by the airline industry as “odour”. This “odour” however, can signal the presence of highly toxic substances, including carbon monoxide fumes.
Despite all the promises given in marketing videos launched by many airlines in the past weeks telling the public that the air is as clean as in an OR or hospital: it is not! Any number of viral load can be brought on board by any (asymptomatic) person, who will not be detected by any fever measuring or other health check, and there is no guarantee that there would be no health hazardous fume emissions entering the cabin breathing air at any given time.
Airlines claim that aircraft cabin air quality is comparable to hospitals’ operating rooms “cleanroom” air quality.
Apparently the airline industry considers demands for a free middle seat because of Corona to be excessive. There is "a very low risk of virus transmission on board", they state, and „the majority of commercial aircraft are equipped with highly effective particle filters"; however, they do not offer any information which aircraft exactly are fitted with filters, nor what these filters filter. They simply keep repeating, that “these highly efficient filters“ clean the cabin air in such a way that it is "comparable with the sterile environment in a hospital operating room"1)
They point out that their filters have a 99.999% filtering efficiency of bacteria, fungi and viruses, and make it sound like that there is no danger of infection.(Pall)
After a little digging one finds that testing was performed on only two bacteria types – both of which are larger in size than a 0.3micron HEPA filter opening. On the Pall Aerospace website we can read that there is a 99.999% removal when challenged with the „Brevundimonas diminuta“ which is a bacteria commonly used as a test organism for validation of sterilizing-grade membrane filters due to the small size of the bacterium; they mention the „Bacillus subtilis“ which is considered a benign organism as it does not possess traits that cause disease, and the “MS2 Coliphage” virus which is generally applied as a surrogate for pathogenic respiratory viruses, such as influenza, as it is safe for personnel to handle and requires less time and labor to measure virus infectivity.
But the MS2 coliphage which is about 27 nm in diameter was not determined to be a sufficient surrogate for influenza A virus with respect to droplet persistence when applied to the N95 FFR as a droplet.
Virions, or “particles”, of coronary viruses are spherical particles between 0.06 micron and 0.14 micron in diameter, averaging about 0.125 micron, measured by electron microscope (Zhu et al, 2020). This means that coronavirus particles are smaller than PM2.5, but larger than some dust and gas particles. 7)
So, we know that the majority of viruses are typically less than 0.3microns. Testing was performed on only one virus. How was a 99.99% removal efficiency result achieved? How can virus and bacteria removal efficiency be identical considering there is a substantial size difference between them?
Laboratory-generated virus aerosols are commonly produced from liquid suspensions using pneumatic nebulizers such as Collison nebulizers, as the wet-dispersion technique simulates many dispersion processes of viruses in the natural environment The composition of liquid suspensions from which virus aerosols are generated (also known as nebulizer suspensions) is known to affect the infectivity/survival of airborne viruses . Given that many laboratory studies use artificial nebulizer suspensions (e.g., cell culture media) that do not mimic natural release of virus aerosols from body secretions (e.g., human saliva), it may be assumed that the survival of airborne viruses determined in laboratories most likely do not represent that in real-life situations. 8)
A 2017 study by the University of Hong Kong, funded by BOEING, concluded that germicidal “transmission may occur over long distances” and take place via close proximity to infected source, airborne disbursement or fomite route 13), which could explain the excessive aircraft disinfection and cleaning taking place during this pandemic.
Clean air is odorless, colorless and tasteless.
It is rich in oxygen and feels fresh and does not contain any pollutants harmful to health. It should be neutral and thus not carry ions. In general, anything that is toxic or has electromagnetic capabilities will generate harmful positive ions – some examples: toxic carpeting and upholstery, air pollution, especially in crowded cities and industrial zones. Most studies have found that levels of positive ions are extremely high in homes, cities and office buildings 17, 18, 19. Good indoor air does not cause any symptoms typical to indoor air problems, such as tiredness, headaches, itching of the eyes or respiratory symptoms. If something smells odd when you enter an aircraft (stuffy, greasy, smokey, mouldy, gym-like stale air) where there is plenty of carpeting and upholstery it is a sign of poor-quality indoor air. Residue from bleed-air pollution and pesticide spraying sticks to the walls and seats and cannot be cleaned off by rubbing or spraying it down with disinfectant chemicals.
We need approximately 10,000 liters of clean air per day. Without clean air, we can survive for around three minutes, without clean water a maximum of three days and without food about three weeks.
Many people, passengers and aircrew alike, suffer from symptoms caused by poor indoor air on flights. Poor aircraft air quality is not only caused by germs, bugs and viruses, but chemical fume emissions including CO entering the cabin via the engines, from where the “fresh air” is drawn and pollute the air often dangerously.
Research shows that the majority of health problems are caused by particulate matter.
The indoor air quality depends first and foremost on how many people are in the room and how they behave. This influences the air turbulence in the room. It also depends on items in the room (seats, carpets, blankets, hand luggage, purses, cameras etc.). In an OR devices and tools etc. are sterilised - aircraft seats, floors and passenger’s clothes and luggage aren’t.
Trying to work with single factors ( 1 virus, 1 bacteria, 1 –electro-chemical substance) is virtually impossible, even useless, as the result of polluted air stems from a variety of particle pollutants including dust, inorganic fibres, microbes, gaseous pollutants – and in the case of aircraft cabin air pollution up to 127 different substances have been detected (EASA), i.e. formaldehyde, ammonia, carbon dioxide, carbon monoxide, organophosphates, plus benzene, n-hexane VOCs and residue from pesticides. The effect that these air pollutants have on our health depends on their quantity, the combination effect, and the level and duration of our exposure and the individual’s general health situation, since exposure resistance varies dramatically from person to person.
Aircraft air as clean as in an OR?
The same type of HEPA filters, which are being highly praised by the airline CEO’s are commonly also used to filter supply air flow in a “cleanroom” (i.e. OR). However, as mentioned it can only collect particles of 0.3 μm and larger in diameter, which renders a need for additional air decontamination technologies such as air “purifier” units in the (OR) room. The majority of nanoparticles in cleanrooms are process-related and must be effectively removed at the source. While most particles in cleanrooms can be related to human activity, ultra fine particles are also generated by electrostatic discharge19), chemical reactions such as oxidation, and gas phase nucleation. These contaminants cannot be removed with fixed HVAC interfaced HEPA filtering systems.
One can only verify the quality of indoor air by measuring it, which offers information about the quality and purity of the air in real time. As concluded in a 1998 study by Melvin W. First (Harvard School of Public Health): “Standard qualification test tell us very little about the performance of HEPA filters under realistic use conditions” and “Efficiencies observed during standard qualification tests are not necessarily the results that will be obtained in practice”.14)
Measurement and real-time monitoring of measurement results would provide a solid basis for maintenance. The purpose of measurement is to reduce uncertainty in decisions, and that way eliminate the possibility of mistakes in corrective actions.
However, there are no real time measurements made on aircraft and there are no warning sensors installed!
How efficient this type of technology actually is in individual cases depends on the conditions on site, above all, on the actual air quality during the decisive time. “In the case of OR-clean rooms the air quality is usually only comprehensively checked once - before a new or converted operating room is handed over to the user”, Dr Weiss from Klimatechnik says. “Also, on this occasion a turbulence or degree of protection measurement is carried out according to the specifications of DIN 1946-4. This means that during the measurement the room is empty: there is no personnel, no operating table and no instruments.”
The quality of the air depends on how many people are in the room and how they behave in it, which influences the air quality. The same applies to the way in which operating tables, equipment tables and lamps are positioned in the room. It remains unclear what the air quality really is during the operation, how it changes during this time - in short: how efficient the air flow is. 2)
Before entering an operating room, surgeons and nurses etc. have to have washed and changed into sterile clothing (scrubs). Why? To keep the air as free from pollutants as possible. Are aircrew and passengers wearing sterilized clothing? No.
The air is never checked in aircraft!
Apart from HEPA filters do aircraft also have air purifying ceilings installed then? No.
A HEPA filter, whether referred to as medical, commercial, industrial or state-of-the-art, is nothing more than a filter designed to capture “99.999%” particulate matter down to 0.3µm (microns). Viruses, gases and toxic chemicals are much smaller - anywhere from about 0.1µm to 0.0001µm in size.
In their review of HEPA filters, the FAA’s Medical Institute has indicated that HEPA filters are not designed to capture gases, vapors and viruses. Reports and studies by ASHRAE, the Research Council of Norway and the Clemson University have found that HEPA filter efficiency claims of 99.97% (or 99.999%) are generally based on short-term laboratory testing using artificial challenge dust such as: the sodium flame method to BS3928 or DOP testing to Mil Std 282 (15,16). That efficiency claim has little relevance to actual filter effectiveness during long-term usage under actual operating conditions.
Air “purifiers” are a whole specialized technology in themselves, especially for “clean rooms” such as operating rooms, ICU’s etc. Realistically, they need to be capable of simultaneously mitigating germicidal and chemical contaminants. All of the supply air enters the room through these units, while air flow is controlled to create positive pressure difference to outside environment. A second unit is utilized to constantly circulate and purify the air from any process and human-related contaminants.
"Through continuous online monitoring and the corresponding permanent situation-specific regulation of the air flow, we ensure that the particle and germ contamination during the decisive cut-suture time is as low as possible," summarizes Rupert Mack: "This enables us to significantly reduce the number of postoperative infections caused by airborne germs.
And even so, according to the information provided, the TAV ceilings do not provide the necessary protection against germs during operations at the operating table, despite the high energy expenditure for air transport, humidification and dehumidification as well as air temperature control. According to Professor Martin Kriegel, this is due to the fact that the flow of air in the room is disturbed by equipment and OR personnel. This causes the displacement flow in the wound area above the operating table to collapse. "There is no longer any protection against the penetration of germs and particles," says Kriegel. 3)
What makes indoor air poor?
According to a study by Sisäilmayhdistys (Finnish Indoor Air Society), most of the problems are caused by fine and ultrafine particles from outdoor air pollution that people bring with them indoors. It is difficult to determine a single cause of poor indoor air quality as it is usually caused by a combination of factors and calls for a comprehensive approach instead of trying to fix one problem at a time.
Studies have shown that even a single substance or very small concentrations of particulate impurities or their combinations may be harmful to health.
Good indoor air quality can be achieved by preventing harmful emissions and ensuring adequate ventilation. The cleaning of the ventilation system is essential for limiting pollutant emissions, as contaminants will accumulate in the ventilation ducts. In January 2020 „Report Mainz“ a German TV production, proved in their documentary „Toxic Gas in Aircraft Cabin Air - Does it make Passengers & Crews Ill?”, that the aircraft airducts are filthy and full of toxic oily grime; it is impossible to clean the many meters of winding and hidden air ducts as they can’t even be reached without taking the aircraft apart and so the additional unfiltered air contamination source is obvious.
According to a two-year study by microbiologists and engineers at Auburn University, the problem areas for germs on planes, when not cleaned properly, are airline seat upholstery, tray tables, armrests, seatback pockets and the lavatory handles. The study found that bacteria can live for up to a week on such surfaces. In a deep cleaning, the ceiling, walls and overhead bins are sanitized, floor and cloth seats shampooed, and synthetic seat covers disinfected. There currently is no single industry standard for deep cleaning. In the past, there could be a lapse of as much as 90 days between such cleanings. Traditionally, the Federal Aviation Administration (FAA) does not regulate or inspect aircraft cleaning, leaving frequency and thoroughness up to individual airlines.
In conclusion:
The recirculated air on-board aircraft, which accounts for approximately 50% of the air supply, can contain high concentrations of dust, skin flakes, viruses, and other microorganisms whilst common occurrences like coughing and sneezing, combined with ultra-low humidity can promote the spread of bacteria and viruses and increases the risk of static electricity causing damage to equipment and additional discomfort to people.
The remaining 50% of the cabin air is provided by the engine bleed air. This air can contain volatile organic compounds (VOCs) as a result from pyrolised engine oils that create unpleasant smells. However, such “smells” are not always harmless but more often than not, toxic, causing acute symptoms such as light headedness, headaches, nausea and dizziness, to name a few, and indeed can become long-term harmful to our health.
Despite all the pretty promises and colorful, music underlined marketing videos launched by many airlines in the past weeks, with a pleasant voice telling us that the air is as clean as in an OR, or hospital: it is not! Any number of viral load can be brought on board by any (asymptomatic) person, who will not be detected by simple fever measuring or other quick health checks.
If the virus and ensuing illness are as dangerous as is said, we highly suggest that you wear a high grade mask, at minimum an FFP2 (N95) or FFP3 (N99) and best one with a valve. For additional protection a small travel air purifier which emits healthy negative ions to hang around your neck might also be a good idea, and finally: keep the air vents above your seats closed.
A statement like this one: "The health and safety of passengers, crews and employees have the highest priority for us (the airlines)" – “… appears cynical against this background and remains purely lip service” , as stated by in a recent interview by Professor Dieter Scholz from the Hamburg University of Applied Sciences’ Department of Automotive & Aeronautical Engineering 12).
Acknowledment:
I would like to thank Rein André Roos / PhD-Ing. and Reinhard Schuetz /Eng. for supporting me and providing me with assistance, advice and technical feedback.
Note:
Short excerpts and quotes from other authors have been used under the’ fair use policy’ for educational purposes. All rights © reserved to the respective authors as listed.
Trusted Research Sources
1) https://www.airliners.de/a4e-mittelsitz-corona/55314?fbclid=IwAR3lqWCQrJi7YwaJN1gMkenBBfV1oFJYGmLpm7QcFdJhpvmC8ZfDZrlqv_Y
2): https://www.management-krankenhaus.de/topstories/hygiene/konstantes-online-monitoring-der-luftqualitaet-im-op
3) https://mail.google.com/mail/#inbox?compose=CllgCJfrLftMvhMXXKbbGbLXQbQjpXGlDfxvrhnLjnrmrDDMvWdgPjWQJGcZllsMgjGtZMnwhqB and https://www.tab.de/artikel/tab_Belueftung_in_OP-Raeumen_2864301.html
4) https://pubmed.ncbi.nlm.nih.gov/11977409/
5) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4615560/
6) https://aem.asm.org/content/77/1/229
7/8) https://aem.asm.org/content/80/9/2796
9)https://www.tandfonline.com/doi/full/10.1080/02786826.2012.754841
10)http://medicalsystems.sanova.at/download/laminarairflowmobil/toulpostop.pdf
12) https://youtu.be/HdvprC-knhY / https://purl.org/corona/pr2020-06-05
13) https://onlinelibrary.wiley.com/doi/epdf/10.1111/ina.12445
14) https://journals.sagepub.com/doi/pdf/10.1177/109135059800300111
15) https://www.sciencedirect.com/science/article/abs/pii/S0032591016303849
16) https://www.ashrae.org/File%20Library/Technical%20Resources/Technical%20FAQs/TC-02.04-FAQ-68.pdf
17) IONS https://www.britannica.com/science/ion-physics
18) IONS https://www.britannica.com/science/nervous-system/The-ionic-basis-of-electrical-signals#ref606353
19) http://www.appstate.edu/~clementsjs/journalarticles/glor.pdf
20) BleedAir https://krex.k-state.edu/dspace/bitstream/handle/2097/19022/JakeRoth2015.pdf?sequence=4
