Aerosolized Transmission

This forum is to discuss general things concerning TSOI.
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Re: Aerosolized Transmission

Post by trader32176 »

Coronavirus is in the air — there’s too much focus on surfaces
Catching the coronavirus from surfaces is rare. The World Health Organization and national public-health agencies need to clarify their advice.


A year into the pandemic, the evidence is now clear. The coronavirus SARS-CoV-2 is transmitted predominantly through the air — by people talking and breathing out large droplets and small particles called aerosols. Catching the virus from surfaces — although plausible — seems to be rare (E. Goldman Lancet Infect. Dis. 20, 892–893; 2020).

Despite this, some public-health agencies still emphasize that surfaces pose a threat and should be disinfected frequently. The result is a confusing public message when clear guidance is needed on how to prioritize efforts to prevent the virus spreading.

In its most recent public guidance, updated last October, the World Health Organization (WHO) advised: “Avoid touching surfaces, especially in public settings, because someone with COVID-19 could have touched them before. Clean surfaces regularly with standard disinfectants.” A WHO representative told Nature in January that there is limited evidence of the coronavirus being passed on through contaminated surfaces known as fomites. But they added that fomites are still considered a possible mode of transmission, citing evidence that SARS‑CoV-2 RNA has been identified “in the vicinity of people infected with SARS-CoV-2”. And although the United States Centers for Disease Control and Prevention (CDC) says on its website that surface transmission is “not thought to be a common way that COVID-19 spreads”, it also says that “frequent disinfection of surfaces and objects touched by multiple people is important”.

This lack of clarity about the risks of fomites — compared with the much bigger risk posed by transmission through the air — has serious implications. People and organizations continue to prioritize costly disinfection efforts, when they could be putting more resources into emphasizing the importance of masks, and investigating measures to improve ventilation. The latter will be more complex but could make more of a difference.

The New York City Metropolitan Transit Authority alone estimates that its annual COVID-related sanitation costs will be close to US$380 million between now and 2023. Late last year, the authority asked the US federal government for advice on whether to focus solely on aerosols. It was told to concentrate on fomites, too, and has so far directed more resources towards cleaning surfaces than tackling aerosols.

Now that it is agreed that the virus transmits through the air, in both large and small droplets, efforts to prevent spread should focus on improving ventilation or installing rigorously tested air purifiers. People must also be reminded to wear masks and maintain a safe distance. At the same time, agencies such as the WHO and the CDC need to update their guidance on the basis of current knowledge. Research on the virus and on COVID-19 moves quickly, so public-health agencies have a responsibility to present clear, up-to-date information that provides what people need to keep themselves and others safe.
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Re: Aerosolized Transmission

Post by trader32176 »

New project to improve air filtering in ambulances

2/4/21 ... ances.aspx

Cranfield University is working with Q-Flo, Cambridge University and NHS England to record experimental airflow data from a modern NHS ambulance under different driving conditions.

Collection of the data, which is being funded by the Royal Academy of Engineering, will explore the effective installation of filtration units which are able to remove virus molecules, including COVID-19 aerosols.

Professor Helen Atkinson CBE, FREng, Pro-Vice-Chancellor - Aerospace, Transport and Manufacturing at Cranfield University, who is overseeing the project, said: "We're very pleased to be able to support the Royal Academy of Engineering's Engineering X Pandemic Preparedness scheme along with our project partners Q-Flo, Cambridge University and NHS England.

"There are currently nearly 30,000 paramedics in the UK and thousands of ambulances nationwide. Airflow patterns inside ambulances are complex and not well documented - mapping these flows will enable the optimized installation of filtration systems and reduce the potential exposure of NHS ambulance crews to COVID-19 aerosols in their vehicles."

" SCAS, on behalf of the NSAFG, is very pleased and excited to be involved with this project and is fully committed to working with the group in an area that has been a challenge for ambulance services and the NHS for numerous years.

The success of this project will be extremely positive for the patients we carry and care for as well as assisting our ambulance crews across the UK and potentially the world in delivering the highest care they can give to patients."

- Phil Pimlott MBE, Assistant Director Operations South Central Ambulance NHS Foundation Trust (SCAS) and Chair of the UK National Strategic Ambulance Fleet Group (NSAFG)

The project will provide flow maps from the ambulance interior over a range of driving conditions up to 70 mph. COVID-19 aerosol sizes, that can be inhaled, are generally less than 10 microns in diameter and particles of this size tend to follow flow patterns without settling onto surfaces.

Dr Adam Boies, Reader in the Department of Engineering at the University of Cambridge and partnership director in the Aerosol Centre for Doctoral Training, said: "Effective filtration strategies for PM10 particles are increasingly seen to return environments to safe levels of operation following viral release whereby suspended particles that remain after droplet drying may remain indefinitely without dilution or active removal."

The flow data will facilitate the integration of an active virus filter (AVF) system - TorStranTM - developed by Q-Flo Ltd, which takes in contaminated air and captures individual virus molecules, including those contained in airborne droplets, then destroys the virus molecules and returns clean air to the environment.

Martin Pick, Chief Operating Officer of Q-Flo, said: "The collaboration with Cranfield has been positive and perfectly timed. The TorStran™ Activer Virus Filter will help to keep people safe, reducing the risk of infection, but it is critically important that we understand where to position the unit to ensure maximum effectiveness."

Knowledge of the flow field is key to allowing Q-Flo to effectively integrate their filtration system into NHS ambulances. The current filtration design is at an advanced phase, meaning a significant roll out of the product could occur in the next 12 months.

Work to collect the data is already underway and a flexible mounting system has been fitted inside an ambulance interior for the light source and imaging system. Calibration and testing of the flow visualisation system in a stationary and moving ambulance has already begun, enabling the acquisition of image datasets from selected regions of the vehicle.

Cranfield's Multi-User Environment for Autonomous Vehicle Innovation (MUEAVI) - a 'smart' road test environment, which is a first of its kind in the UK, built alongside a research airport within the controlled setting of a university campus - is being used in the research for instrumentation testing and data capture at low speeds with an emergency 999 ambulance provided by SCAS.

Data from the project will be openly published, allowing other vehicle designers to improve their ventilation systems.

The project is also expected to lead to other larger projects, such as modelling of airflows in vehicles using computational fluid dynamics, leading to greater refinement of vehicle filtration systems.

The approach will also aid cabin design and provide leverage for further work to measure and model flows in other significant transport systems, such as buses, aircraft and trains, where COVID-19 infection still presents known risk. Any future pandemic will also benefit from the knowledge gained in this research.


Cranfield University
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Re: Aerosolized Transmission

Post by trader32176 »

Virus transmission by dental tools and prevention by antiviral agent

2/16/21 ... agent.aspx

Dental procedures present a potential for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission due to the extensive generation of droplets and aerosols during the use of power-driven instruments.

Researchers at the University of Ljubljana have demonstrated how a virus can spread by droplets during ultrasonic scaler (USS) operation and how this spread can be mitigated by merely substituting the irrigant with clinical virucidal agents, namely sodium hypochlorite and EOW (Electrolyzed Oxidizing Water). The study is currently available on the bioRxiv* preprint server.


Dental procedures are a potential way of infection transmission. Power-driven instruments, such as ultrasonic scaler (USS), high-speed rotary instruments, and air-and-water syringes, generate extensive droplets and aerosol. It is reported that contamination occurs up to 3 meters from the patient's mouth.

This contamination is generally reduced by way of mouth-rinsing before the procedure or using povidone-iodine and chlorhexidine gluconate as an ultrasonic liquid compared with distilled water.

During the COVID-19 (coronavirus disease 2019) pandemic, caused by SARS-CoV-2, the focus of dental procedure-associated transmission has rapidly changed from bacteria to viruses. However, to date, there is no research on virus transmissions associated with dental procedures.

The study

The researchers developed an experimental model to study virus transmission during the USS instrumentation and examined the prevention of spreading by replacing the coolant with an antiviral agent. The researchers observed that the virus was transmitted mainly by droplets and up to the distance of 45 cm by USS activity. The tests with aerosol produced inconclusive results.

This study used the Equine Arteritis Virus (EAV) - a non-human viral pathogen resembling SARS CoV-2 in structure and genome. EAV is an animal pathogen, species-restricted to Equidae members. EAV is an enveloped virus with a single-stranded, positive-sense RNA genome and is transmitted in aerosols through the respiratory route.

The researchers designed an experimental setup to demonstrate the EAV spread by USS action. It is well established that the contaminants during the operation settle primarily on the operator's dominant arm, eyewear, and chest of the patient. It was observed to a lesser extent on the nondominant arm and chest of the operator and assistant. Likewise, the EAV predominantly spread via larger droplets (splatter) that reached the immediate surrounding area on the plates up to the distance of 45 cm from the USS tip.

"To the best of our knowledge, this is the first proof of the contribution of a USS action to the spread of the virus via droplets to the environment."

While the researchers were able to detect the EAV in low concentrations in the air sample, they did not achieve a reproducible collection of the infectious virus from the air-sampler.

This is consistent with reports from hospital settings where the air samples tested positive for SARS-CoV-2 RNA and the viable virus in small percentages (17.4% and 8.6%, respectively). The researchers attribute the reason to this: 1) by calculating the virus concentration per aerosol, which was a small fraction of particles harboring a virus, and 2) by explaining possible virion damage during sampling.

To prevent the droplet spread of the virus to the surroundings, the researchers changed the saline coolant with EOW or hypochlorite. They noted that both the virus inactivation and absence of cytotoxicity were achieved at 0.25% hypochlorite.

The researchers looked for a specific cytopathic effect (CPE) - with the cells rounding and degeneration of the cell monolayer occurring. In the control, where they used saline, they observed the virus infection even at a greater distance from the tip.

Compared to the practical results from using the hypochlorite, the researchers observed that EOW produced no cytotoxicity and no infection at all. The researchers claim that this is the first study that has clearly shown the possibility of disinfecting the virus in droplets generated by USS by replacing inert coolant with antiseptic irrigant.


Because the SARS-CoV-2 is present in the saliva, gingival crevicular fluid, nasopharyngeal, oropharyngeal and bronchial excretions, the dental procedures represent a high risk of SARS CoV-2 virus transmission. Here, the researchers present the first dental procedure virus transmission study, performed with a viable virus evaluation.

Importantly, this study shows that the virus droplet transmission could be prevented by a simple saline replacement with a virucidal agent that has already been tested as mouth-rinse for home oral care.

This study has shown EOW as an effective virucidal tool in dental procedures in a huge leap for disinfection in dental settings during this pandemic. The approach addresses both direct and indirect contamination of surfaces - effectively preventing transmission of the virus.

*Important Notice

bioRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

Virus transmission by ultrasonic scaler and its prevention by antiviral agent, Aleš Fidler, Andrej Steyer, Rok Gašperšič, bioRxiv 2021.02.10.430630; doi:, ... 0.430630v2
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Re: Aerosolized Transmission

Post by trader32176 »

Does climate play a large role in SARS-CoV-2 transmission?

2/19/21 ... ssion.aspx

The emergence of the novel coronavirus disease (COVID-19) was first reported in Wuhan, China, in December 2019 and its rapid spread across the world has caused the World Health Organization (WHO) to announced a Public Health Emergency of International Concern (PHEIC). COVID-19's causative pathogen – severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – is highly contagious and spreads rapidly through the respiratory droplets from infected individuals. Most people infected with COVID-19 develop mild symptoms or are asymptomatic. For the others, it may cause acute respiratory problems, severe health issues and in some cases, it may also prove to be fatal.

Scientists across the globe have been fighting to curb the spread of the disease by devising various approaches such as the development of vaccines, nasal sprays, sophisticated masks, oral medicines, and many more. They are also working to establish valid links between environmental conditions and the coronavirus infection rate to develop a better understanding of the nature of the virus and how it spreads.

In a new paper released on the medRxiv* preprint server, a team of researchers from the Universidade Federal de Itajuba in Brazil has reported that weather plays a vital role in determining the transmission rate of SARS-CoV-2 infection. They have further stated that after controlling for parameters such as age, population, and urbanization, the meteorological variables are highly significant for predicting mortality rates of a region. During the early days of the global outbreak of COVID-19 in early 2020, it was wrongly assumed that the virus thrives only in cold conditions. However, the subsequent intense spread of the coronavirus in many tropical countries such as Brazil and India have challenged this misconception.

Recently, the correlation between the spread of SARS-CoV-2, and meteorological variables such as temperature, wind speed, relative humidity, and precipitation of urban-rural sparsely populated cities located in southeastern Brazil was analyzed. For this study, researchers collected meteorological data for the six study locations from the Federal University of Itajubá (UNIFEI, 2020) and the National Institute of Meteorology (INMET, 2020) for the period of April to December, 2020. The daily data of COVID-19 cases were procured from the database of the Secretary of Health of the Government of Minas Gerais state (SHGMG, 2020). The correlation study was conducted using Spearman's correlation coefficient.

In the first year of the pandemic, the study revealed a lower incidence of COVID-19 in less densely populated areas (i.e., the study area for the experiment). This is in contrast to the high infection rates in other more populated regions of Brazil. Scientists initially hypothesized that the lower number of cases was perhaps due to the better air quality in smaller cities.

Many prior studies have suggested that relative humidity plays a significant role in the persistence and transmission of the virus in a closed environment or indoors. An increase in virus transmission takes place when relative humidity is low. Similar studies conducted in various regions of the world such as New York City, Chinese provinces, and South American regions indicated a significant correlation between the daily incidence of COVID-19 cases and absolute humidity. The current study under consideration further confirmed that irrespective of the level of pollution, the rate of transmission of the virus is high at lower levels of relative humidity.

Many scientists have also reported that maximum and minimum temperatures are positively correlated to virus transmission. The current research corroborates these findings and indicates that an increase in temperature and a decrease in relative humidity aid in the transmission of the SARS-CoV-2 virus.

In many cities, wind speed showed a positive correlation with the incidence of COVID-19. However, researchers claim that this result might not be conclusive because of various reasons. For example, wind speed disperses pollutants present in the atmosphere. In the regions where the wind speed is high, a lesser amount of contaminant prevails. Further, wind speed varies from one region to another; for instance, coastal regions will have greater wind speed than inland. Therefore, more research is required to determine a correlation between the COVID-19 incidence and wind speed.

Researchers have further reported that daily accumulated rainfall and COVID-19 infection are not correlated. However, in another study conducted in Oslo, Norway, scientists found a significant correlation between lack of precipitation and increased COVID-19 cases.

The current study helps the scientific community to understand the relationship between climatic conditions and the spread of SARS-CoV-2 in the less densely populated regions. Such evaluations assist the scientists in designing preventive measures to stop the spread of the disease and thereby contain the pandemic. The outcome of this research is also expected to assist in the framing of appropriate and more efficient mitigation policies, against the spread of SARS-CoV-2, on the basis of local climatic profiles.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

Marcelo de Paula Correa, Ana Leticia Campos Yamamoto, Luiz Felipe Silva, Ivana Bastos, Talis Matias, Raquel Pereira, Flavia Fagundes, Alysson Ribeiro, Joaquim Moraes, Filipe Silva. (2021) Are there significant correlations between climate factors and the spread of COVID-19 for less densely populated and less polluted regions? doi:, ... 21251129v1
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Re: Aerosolized Transmission

Post by trader32176 »

New evidence of SARS-CoV-2 spreading on planes

2/28/21 ... lanes.aspx

New research from the Centers for Disease Control and Prevention (CDC) journal Emerging Infectious Diseases analyzed a case showing in-flight transmission of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) despite passengers getting tested before departing to New Zealand.

Since the first coronavirus wave, New Zealand has had an exceptional response to the pandemic with a system of managed isolation and quarantine for people entering the country. The restrictions also expanded to include testing people for COVID-19 on the third and twelfth day of quarantine.

The world currently has over 114 million global cases and over 2.53 million deaths. New Zealand has some of the lowest cases around the globe reporting approximately 2,378 cases and 26 deaths.

The study “Genomic Evidence of In-Flight Transmission of SARS-CoV-2 Despite Predeparture Testing” may help scientists and public health officials further understand the exact risk of coronavirus transmission on long flights. The international research team, led by Tara Swadi from the New Zealand Ministry of Health, writes:

“Combined, these data present a likely scenario of >4 SARS-CoV-2 transmission events during a long-haul flight from Dubai to Auckland. These transmission events occurred despite the reported in-flight use of masks and gloves. Further transmission between travel companions then occurred after the flight, in a MIQ facility.”

Details on COVID flight transmission between seven passengers

The team gathered case data from a coronavirus outbreak on a plane on September 29, 2020, arriving from Dubai, United Arab Emirates, to Auckland, New Zealand. During the 14-day managed isolation and quarantine, 7 people tested positive for SARS-CoV-2. The researchers collected data from the Ministry of Health collection for epidemic surveillance.

All 7 passengers infected with SARS-CoV-2 came from 5 different countries, and 5 were tested negative on one layover stop in Malaysia. All 7 passengers were seated 4 rows away from each other during an 18-hour flight. During the flight and before leaving the Dubai airport, mask-wearing was optional. Five of the 7 infected passengers wore masks and gloves while on the plane, while 2 did not.

Genomic SARS-CoV-2 data

The researchers performed whole-genome sequencing on the test samples of the 7 patients positive for SARS-CoV-2. They found the sequences were genetically identical, and with the exception of one mutation from one passenger, all SARS-CoV-2 samples came from the B.1 lineage.

The researchers then compared the 7 genomes to the international database (GISAID) also found 6 identical genomes, with 4 coming from Switzerland and 2 from the United Kingdom.

Tracking down the source

Based on the results, the team predicts 2 passengers were the source of infection. These passengers had traveled together from Switzerland and had tested negative three days before leaving the country. One of these passengers was the first to report symptoms of COVID-19 infection on October 1, with a positive SARS-CoV-2 test result the following day.

In addition, they predict 4 passengers became infected during the flight, and one passenger became infected while in mandatory quarantine.

Limitations in genomic surveillance pose difficulty in finding the source of transmission

However, the researchers suggest limited global sequencing data makes it hard to narrow down the source of the SARS-CoV-2 outbreak on the plane.

“These findings were consistent with virus introduction onto the airplane from Switzerland by passenger A, B, or both. Nevertheless, accurately identifying the source of this outbreak may be impeded by substantial biases and gaps in global sequencing data; hence, we cannot explicitly exclude passenger C as the source.”

There’s also the possibility of an alternative exposure event, such as SARS-CoV-2 transmission at the Dubai airport before boarding. Although, they suggest the close seating makes in-flight transmission a likely option.

“Although not definitive, these findings underscore the value of considering all international passengers arriving in New Zealand as being potentially infected with SARS-CoV-2, even if pre-departure testing was undertaken, social distancing and spacing were followed, and personal protective equipment was used in-flight.”

Journal reference:

Swadi T, et al. Genomic Evidence of In-Flight Transmission of SARS-CoV-2 Despite Predeparture Testing. Emerging Infectious Diseases, 2021. doi: 10.3201/eid2703.204714, ​
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Re: Aerosolized Transmission

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Speaking whilst infected with COVID-19 may cause it to spread

3/8/21 ... pread.aspx

In this interview, News-Medical speaks to Dr. Keiko Ishii about her research efforts during the COVID-19 pandemic and how speaking whilst infected can cause the virus to spread, and why wearing masks is so important.

What provoked your research efforts into the COVID-19 pandemic?

Our research started when Professor Onishi of Yamano College of Aesthetics in Japan asked me for an image that would help to prevent the spread of infections at a beauty salon.

It is natural to be careful about sneezing and coughing in people who have symptoms. However, it has been identified that coronavirus can also be asymptomatic and that these people can be infectious, which may cause explosive spread.

A beauty welfare researcher at Yamano College of Aesthetics said that we should be careful about aerosol infection during customer service to prevent the spread of infection. It is important to understand these phenomena and thoroughly take measures against infections. This can allow professionals to provide beauty and long-term care in order to prevent economic stagnation and maintain quality of life, whilst showing peace of mind to avoid social turmoil.

For infection control to be widely recognized and implemented, it is important to show it not only in the words of experts but also in easy-to-understand photographs and videos.

Since I usually specialize in visual measurement of flow and temperature in thermal engineering and fluid engineering research, I was asked for technical cooperation in acquiring the exhalation images. I had thought that it would only be biology and medical personnel who could contribute to solving the coronavirus problem, and so I was happy that despite specializing in engineering I could contribute to coronavirus infection control by participating in this project.

I had not studied breath flow before this. At first, my aim was just to take some pictures that gave the message, "If you do not wear a mask, you are more likely to get infected! Everyone should wear a mask!".

However, while shooting with various posture patterns with or without a mask and with or without a face shield, I noticed that the tendency of flow changes according to physical rules. When I examined past research, this had not been reported, and so I decided to summarize them as a treatise.

How is COVID-19 spread?

There are various routes to disease infection and the risk of aerosol infection has been discussed in recent years. Currently, there are no quantitative studies on the levels of aerosol exposure that can cause infection.

In the past, measures against infectious diseases, airborne infections and droplet infections have been mainly discussed. Measles is an example of a highly infectious virus that causes airborne infection, but it is understood that COVID-19 does not have enough infectivity to cause airborne infection. Here, it is important to understand the difference between airborne and aerosol infections.

Currently, there is no clear definition for aerosol infection. Most of the droplets from coughing and sneezing have a size of 5 μm or more and are heavy, so they disperse to about 1 to 2 m. These can be suppressed by wearing a mask. It is said that among the droplets emitted by coughing, sneezing, and speech, fine particles of 2 to 3 μm or less diffuse widely and float in the air for several hours.

Even in our experiment, particles of 1 µm or less floated in the air for a long time. Normally, minute aerosols dry quickly, and it is believed that the virus does not remain infectious for a long time in the dry state.

It has also been reported that the deposition rate in the nasal cavity and upper respiratory tract is relatively low compared to particles of 5 μm or larger. However, it has been pointed out that in a densely populated area, damp environment, or in a closed environment, the aerosol containing the virus may continue to float in the air for a long time while retaining moisture and infectivity.

Aerosol infections are beginning to be thought of as a major cause of the spread of the virus, as many infection clusters have been reported in dense and closed environments.

How do air droplets spread viruses and cause infection?

From the information currently available, we believe that inhaling a large amount of fresh aerosol that has just been exhaled by an infected person or exposing it to the mucous membrane will increase the probability of infection.

As mentioned above, close proximity in a closed, humid environment will keep the virus active and more likely to cause infection. It is easy to forget because the particles and the air are invisible, but even with speech and breathing, the airflow changes drastically. If you communicate with each other without a mask in a short distance, you will always inhale the freshly exhaled aerosol.

In this study, even if you just mumbled such as you might in a business situation, the aerosol diffused 50 cm in a few seconds without a mask. I think that the risk is higher if you talk with a friend where you may be talking louder or laughing out loud.

Without a mask, the exhaled breath moves toward the front of the body due to the inertia force and diffuses randomly. If you wear a mask, the aerosol stays on the surface of your body and rises due to the heat of the body, preventing the aerosol from hitting people around you directly.

It is thought that once the aerosol has risen, it will continue to float and then come down; however, since the traveling distance will be longer, theoretically the water will evaporate during this period and the infectivity will decrease.

Masks are useful when facing each other at similar face heights to prevent contact with the fresh breath of another person. Furthermore, when you wear a mask, the aerosol rises from the top of your head. It flows between the scalp and the hair and is released from the top of the head. The scalp of an infected person wearing a mask is a warm and moist environment, and the exhaled breath containing the virus is constantly passing through.

It is better not to touch your mouth or eyes, pick your nose, or grab a sandwich and eat after touching the scalp or hair of another person without washing your hands. This is not just limited to beauticians and caregivers. We often get careless.

Can you describe how you carried out your latest research into COVID-19 and speaking and what you discovered?

I was able to carry out this experiment because of the professors at the Yamano College of Aesthetics and their enthusiasm for social contribution, and the interdisciplinary research organization of the Aoyama Gakuin University which induced me with a sense of responsibility.

Fortunately, the particle size of the exhaled aerosol and the particle size of an electronic cigarette was similar. The viral aerosol particles are problematic for infection, so we decided to use the electronic cigarette for the tracer particles. The liquid of the electronic cigarette was nicotine-free, and we took steps to make sure it was a healthy experiment for participants. A 3W laser sheet was irradiated and we photographed the scattered light of the smoke of the electronic cigarette with a camera.

The experimental system was very simple and is common in fluid experiments. However, in general, airflow experiments commonly use oil mist or dust for the tracer, which is not suitable for human experimentation. To avoid health hazards, we decided to use electronic cigarettes.

We adopted this method with the advice of Mr. Mikami of Kato Koken co. Ltd, a company specializing in optical measurement systems. All of our staff were non-smokers, and so it was hard at first. The exhaled breath behaved differently than originally expected, which was curious. When I summarized it according to the postural conditions, it became clear that the breath was moving according to the thermohydrodynamic mechanism.

What role do masks and face shields play in preventing the spread of COVID-19?

It is well known that large droplets fly forward without a mask. It is important to wear a non-woven mask, as both exhaled aerosols and large droplets will not fly forward if you wear a non-woven mask. In contrast, urethane masks (which are popular in east Asia) and cloth masks can suppress large droplets, but allow exhaled aerosols to pass through.

By wearing a mask, the expiratory aerosol that has stagnated on the surface of the body slowly rises along the surface of the body due to the warmth of the body. This eliminates the exhaled aerosol that has just come out of the mouth directly hitting others.

Shortly after the pandemic began, it was widely recognized in Japan that face shields alone were meaningless. The face shield alone cannot effectively block droplets and aerosols. What was discovered in this study is that when facing down, the exhaled aerosol leaking from the upper and lower ends of the mask, even with the mask, is disturbed and heads downward.

Here, it was found that when the face shield and mask were worn, the exhaled aerosol became more likely to stay on the surface of the body, and the warmed aerosol did not go down. In other words, when a caregiver, a medical professional, a cosmetologist, or a masseuse approaches a person underneath, it is thought that the exposure dose of exhaled aerosol can be effectively reduced by wearing both a mask and a face shield.

What advice would you give to people that are visiting services such as hair salons and medical rooms?

I think it is a good idea to have a doctor or beautician always wear a non-woven mask. As mentioned above, the exhaled breath of a person who faces downwards tends to move downwards while being disturbed, even when wearing a mask.

For this reason, when lying down and undergoing treatment, there is a high possibility that the practitioner's exhaled aerosol, approaching from above, will hit the customer’s body. If you wear both a mask and a face shield, the exhaled aerosol will move upward along the service operator's body, preventing it from traveling to the customer below.

When facing upwards, the expiratory aerosol tends to diffuse upwards in a turbulent manner, even with a mask or face shield. This makes it difficult for practitioners approaching from above to avoid exhaled exposure. I feel that many jobs with a high risk of COVID-19 infection tend to be the type in which customers lie down and receive services, but I think that this is also related to the flow characteristics of exhaled breath.

When lying down, instead of being completely horizontal, if you wear a mask and lie with an inclined backrest, the exhaled breath tends to rise straight from the forehead. If the customer lies down with the backrest tilted to some extent and the practitioner understands that the updraft of exhaled air is generated from the customers' forehead, the practitioner will not be exposed to the exhaled breath directly.

At a beauty salon, the mask is an obstacle for customers when shampooing or cutting. With the mask on, exhaled breath rises from the crown. Without a mask, the exhaled breath tends to stagnate in front of the customer. In either case, the exhalation is not positively directed toward the practitioner who is behind or to the side, so I think that the presence or absence of the mask of the sitting customer does not affect the infection to the practitioner to that extent.

Do you believe that with further understanding of COVID-19, we can help to reduce its spread?

When the spread of COVID-19 began in 2020, it was said that the rate of spread of infection was slower in East Asian countries such as Japan than in Europe and the United States. I think there are various causes for this.

One of the factors is that East Asia is a culture with little skinship, is accustomed to wearing masks, and shampoo their hair a lot. I think that this cultural human behavior was related to the spread of infection.

From the results of this study, I feel that reducing skinship, wearing a mask, and shampooing are important actions to reduce the risk of infection. I think that it is possible to reduce the spread of infection by understanding when the risk of infection is high and changing our lifestyles.

The video I took was featured on Twitter and so on. There was a surprisingly large response, and I saw many responses fearful of exhalation. It is dangerous to be too scared, but I feel that this is one way to raise awareness of the danger of infection in society, visualizing what is invisible.

What are the next steps in your research?

Originally, I was not specialized in exhaled breath flow, but I think it would be interesting to examine the effects of movement of the human body, differences in the surrounding environment, and interference between the exhaled breaths of two people.

Since the quantitative study of aerosol infection has not been conducted, it may be useful to verify how much labeled aerosols settle in the nasal cavity and lungs of mammals. I would like to continue doing a lot of research without being bound by the field.

Where can readers find more information?

The article can be found here: “Relationship between human exhalation diffusion and posture in a face-to-face scenario with utterance”. Physics of Fluids.
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Re: Aerosolized Transmission

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Air purification technologies to combat SARS-CoV-2

3/17/21 ... CoV-2.aspx

The onset of the COVID-19 pandemic had people sharing an array of strategies for disinfection and disease prevention. The ensuing months showed that the SARS-CoV-2 virus is primarily spread through the air via contaminated droplets, prompting a new wave of air purifying technology. A feature article in Chemical & Engineering News, the weekly newsmagazine of the American Chemical Society, details the various air purifier technologies and their efficacy against the coronavirus.

Although official guidance from the U.S. Centers for Disease Control and Prevention (CDC) suggests that social distancing and mask wearing are the most effective ways to prevent the spread of COVID-19 indoors, they also state that air purifiers can help reduce airborne contaminants, including viruses. These gadgets rely on various technologies, writes special correspondent Mark Peplow, and whereas some are proven to work, others require more data. Filtration with high-efficiency particulate air (HEPA) filters made from glass or polymer fibers is the most popular choice in hospitals and other clinical settings.

Another air purification method involves using ultraviolet C (UVC) light to deactivate viruses, including SARS-CoV-2, by making them unable to replicate. However, direct exposure to UVC can be harmful to people, which has led experts to suggest placing the lights in HVAC ducts, or lowering the intensity of the UVC light so that it can't penetrate living cells but can still kill airborne viruses.

Another type of purification is known as bipolar ionization, which uses high voltage electrodes to create positive and negative ions from the air that can then attach to viral particles and prevent them from spreading. Although makers of ionization purifiers tout their ability to combat SARS-CoV-2, experts argue that the research has not been as convincing as that of other methods. Scientists agree that even with air purifiers, masks and social distancing should still be the first line of defense against the spread of SARS-CoV-2.


American Chemical Society
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Re: Aerosolized Transmission

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Coronavirus spread on flight, in hotel corridor, New Zealand study finds

3/18/21 ... index.html

The coronavirus spread on an international flight, in a hotel corridor and then to household contacts despite efforts to isolate and quarantine patients, New Zealand researchers reported Thursday.
Careful genomic tracing confirmed the spread of the virus among nine patients and shows how people can infect one another despite careful efforts, the researchers reported in the journal Emerging Infectious Diseases.
One of those infected had spent 14 days in quarantine after being evacuated on a chartered 747 jet from India to New Zealand last September and had tested negative twice.
Others appear to have become infected on the flight, even though it was only a third full and passengers were spaced apart from one another. All passengers were required to wear face masks for the duration of the flight.

The evacuees were quarantined in a hotel, in rooms with balconies and private bathrooms. But at least two more got infected in the hotel, the researchers reported.
Closed-circuit television shows one of the people infected on the flight and two people infected in the hotel were never in direct contact and were not even outside their rooms at the same time, the researchers said.
"Nevertheless, footage showed that during routine testing on day 12, which took place within the doorway of the hotel rooms, there was a 50-second window between closing the door to the room of case-patient C and opening the door to the room of case-patients D and E. Therefore, we hypothesized that suspended aerosol particles were the probable mode of transmission in this instance, and that the enclosed and unventilated space in the hotel corridor probably facilitated this event," they wrote.

After 14 days of quarantine in the New Zealand city of Christchurch, and repeated negative tests, some of the travelers were flown on a chartered flight to Auckland, where they were met by household contacts. Two of those contacts became infected.
The team tested samples from everyone infected. "We found a genomic link between virus isolated from all 9 case-patients," they wrote.
"These findings reinforce the need for rigorous border control processes for countries pursuing COVID-19 elimination," they wrote. Plus, careful testing and contact tracing is important for keeping track of the virus, they said.
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Re: Aerosolized Transmission

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Can SARS-CoV-2 still be transmissible once symptoms have subsided?

3/22/21 ... sided.aspx

Researchers based at the University of Missouri, in partnership with U.S. government science facilities in Maryland, have reported that individuals severely infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be able to continue shedding infectious viral RNA for over three weeks after the symptomatic infection has passed.

A pre-print version of the research paper is available to read in full on the medRxiv*server.

How does COVID-19 spread?

SARS-CoV-2 is the underlying causative pathogen of the coronavirus disease 2019 (COVID-19) pandemic. Since it was first identified in Wuhan, China, in late 2019, the respiratory virus has spread rapidly across the world. The virus is primarily transmitted through respiratory droplets and salivary contact, and has led to millions being hospitalized with symptoms of fever, fatigue, and difficulty breathing.

Hospitalized patients who recover typically stay for between 10 to 13 days, but in some, the virus may continue replicating even once symptoms have resolved. As a result, these patients will still test positive for the virus, and so are kept hospitalized for longer. It is not known, however, if these asymptomatic, recovered patients are still infectious and pose a threat to the general public.

The research team set out to test the post-recovery infectivity of a male Caucasian patient admitted to hospital with SARS-CoV2. Determining whether these asymptomatic patients pose a risk of transmitting COVID-19 is of great importance, as it may allow for pressure to be taken away from clinicians to withhold positive-testing recovered patients, thus providing more hospital space for future admissions.

What did the scientists do?

The researchers had just one individual in their sample, who they described as a “Caucasian male in his 60s presenting to Urgent Care … diagnosed SARS-CoV-2 positive after three days of disease onset”. Their observations began once he was admitted to the hospital, one week after disease onset. The man was admitted to the Intensive Care Unit on the second day, where he suffered from secondary bacterial pneumonia, eosinophilic bronchiolitis, and oral candidiasis. He eventually recovered and was discharged from the hospital 63 days after admission.

The researchers recorded the patient’s clinical readings at least twice a day and took multiple nasopharyngeal swabs and plasma samples. These samples were tested for viral loads and antibodies. The virus RNA was sequenced and found to belong to the D614G/Q57H/T265I subclade, currently widely prevalent in the U.S.

What did they find?

Current hospital guidelines suggest that patients with improved symptoms, either 20 days post-initial disease onset or 24 hours after any feverish display, may be excused from transmission-based precautions.

The study found, however, that viral shedding can continue much longer this period, for 24 days after symptom onset, implying much longer viral infectivity than previously suspected possible. Additionally, the patient presented with fluctuating viral loads, possibly experiencing a recurrent infection, 54 days after initial virus exposure.

These results are consistent with previous findings, one study concluding that viral shedding may still continue for three months after infection. This therefore indicates that current guidelines are inadequate in preventing the transmission of the virus once symptoms have subsided, and that extended hospital stays “may be necessary.”

The paper is currently in pre-print form and yet to be published, but the authors encourage studies encompassing wider sample sizes to be carried out. Especially so because this study only reported the data of a single patient. The researchers note that the patient suffered from complications during the infection period, and was also on steroid treatment prior to hospitalization, so his results may not be generally applicable to wider populations.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

Wan X, et al. SARS-CoV-2 show no infectivity at later stages in a prolonged COVID-19 patient despite positivity in RNA testing. medRxiv, 2021. doi:, ... 21253228v1
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Re: Aerosolized Transmission

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New device set to revolutionize the resuscitation process for first responders

3/24/21 ... nders.aspx

In response to the COVID-19 pandemic, performance manufacturer Keela Outdoors, NHS Tayside and Scottish Health Innovations (SHIL), have collaborated to design and develop a device that is set to revolutionize the resuscitation process for first responders.

The innovative piece of equipment, named the SARUS-CPR hood, which is an acronym of Safer Airway Resuscitation, was invented by Professor Peter Stonebridge, NHS Tayside’s Medical Director.

It is a small lightweight hood made from transparent fabric which creates a barrier between the patient and the individual performing resuscitation. The hood reduces the risk of contamination and infection from bacteria and viruses such as COVID-19.

The hood has been designed to allow trained CPR responders to easily fit it onto a collapsed patient as soon as they arrive on the scene. This helps to also reduce the time taken to initiate airway ventilation and makes resuscitation much safer for both patients and personnel.

The SARUS-CPR hood can be used by trained personnel in a wide range of settings, including hospitals, GP surgeries and ambulances.

" Frontline healthcare workers and care givers have been absolutely vital to our response to the pandemic and out of all of the challenges of managing the spikes of COVID-19, there has been a lot of innovation in healthcare.

Thanks to the input of other experts in manufacturing and design, the kernel of an idea has been developed into the SARUS-CPR hood and I am very grateful to all the collaborators on this project.”

- Peter Stonebridge, Professor, Medical Director of NHS Tayside

Rod Mountain, NHS Tayside clinical lead for the project, said, “As an NHS worker, I am immensely proud to have been part of its development. This has been a genuine collaborative effort between NHS Tayside and Keela, drawing upon fantastic local engineering and garment manufacturing expertise. COVID-19 drove the innovation, prompting us to look at different approaches to PPE, but we now believe its applications go well beyond the current pandemic.”

" The SARUS-CPR hood is a real testament to home grown collaborative expertise, taking clinician-led insight from the NHS and turning it into a tangible device that’s now ready to be launched onto the market. The teams at NHS Tayside and Keela have played a vital role in realizing that ambition. Their clinical and manufacturing expertise combined with SHIL’s intellectual property and commercialization expertise has accelerated launch onto the market.”

- Robert Rea, Head of Innovation, SHIL

In association with the creation of the SARUS-CPR hood, Keela has previously supported the NHS by manufacturing PPE at its Glenrothes site. At the start of the COVID-19 pandemic, the team expanded the company’s facilities by 10,000 sq. ft and created 50 new jobs to keep up with demand and adhere to social distancing guidelines. Using Scottish-produced fabric from Cupar Angus, the team dispatched PPE to the NHS on a weekly basis.

" With our recent work creating surgical gowns for the NHS at our Keela factory in Glenrothes, we were delighted to be approached by NHS Tayside to be part of the SARUS-CPR hood project. Our team of designers worked in collaboration with the NHS to design, prototype, and engineer the Safer Airway Resuscitation Hood. The device itself is made up of existing CPR airway components encapsulated within a protective barrier hood allowing for efficient adoption in a clinical setting. With the support, guidance, and funding of SHIL, we are delighted to be able to reveal and launch the SARUS-CPR hood.”

- Ruwan Fernando, Managing Director, Keela

As part of the development process the SARUS-CPR hood has undergone extensive trials. It is expected the SARUS-CPR hood will be available for use across the UK later this year.


Scottish Health Innovations Ltd (SHIL)
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