Are Cloth Masks and MERV 8 Filters Aerosol Generators?

Dispersal of Cough Droplets in a Ventilated Room

Swoxid Titanium Oxide Nanofibers Destroy Pathogens

Purdue Researchers Develop Disinfection Aerosol Which is Not a Biohazard

Sinopharm Commits to 337 Tons of Meltblowns for Mask Factories in Hong Kong.

Nonwovens Iberica Purchases Meltblown Line for Mask Products

UPA Healthcare Products Investing in Meltblowns for 86 Million Masks Per Year

UNC Switches from in Person to Remote After 177 COVID Cases

Air Conditioning Unit Purchases Go Hand in Hand with COVID Filtration Opportunities

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Are Cloth Masks and MERV 8 Filters Aerosol Generators?

If cloth masks are aerosol generators they are relatively ineffective in fighting COVID. They could be only 20% effective in reducing  the virus load.

The webinar on masks this Thursday will include discussion and probably debate on this subject.  Many of the recent Alerts have provided evidence which will be available to participants.

We will be asking the researchers to help us understand the whole process including what happens to a large droplet coughed on to a cloth mask interior. The droplets on the mask interior can be visualized as rain drops on a screen. One difference is that with 15 breaths per minute and millions of particles passing in both directions the droplet will be subjected to many forces. The velocity of inhaled air will be relatively uniform across the mask. But the velocity of exhaled air will be uneven.

Surprisingly, the research done on particle size and capture of air pollutants in scrubbers may be very relevant. Venturi and other high energy scrubber efficiency is a function of pressure drop.  The higher the velocity of the particles impinging on the droplets the higher the efficiency of capture.

The breath  velocity through the mask is less than  generated at 2 inches w.g.in a scrubber. But a 50 micron particle if exhaled on to a droplet in the mask would likely penetrate the droplet.

This relationship between velocity and efficiency of capture has been used to create useful and practical particle size analyses. Typical particle size  analysis has been conducted with cascade impactors. McIlvaine introduced the McIlvaine Mini-Scrubber which is a 1 cfm device which has been used by DuPont, Ecolab, the UK government and others as a way to define particle size.

Different methods are needed to measure particle size because

1.      Most particles are not spheres. So diameter is meaningless

2.      The specific gravity of substances vary and this will effect the flow characteristics

It may not be possible to create a measurement technique for virus droplet capture difficulty but it at least should be acknowledged that using particle diameter has limitations.

 

Dispersal of Cough Droplets in a Ventilated Room

Some valuable transport information is contained in the following 2006  analysis. This study aims to understand the transport and dispersal of droplets produced by coughing in a ventilated room. Experiments were conducted to measure the initial velocity and the duration of a coughing burst. Computational fluid dynamics with a Eulerian—Lagrangian model was used to investigate the transport characteristics of evaporating droplets expelled into the ventilated room.

The simulation results indicate that if expelled horizontally the droplets finally settle if their initial size is >100 μm, while if expelled upwards the droplets only settle if their initial size is ≥300 μm.

Different ventilation set-ups vary in their ability to remove droplets produced by coughing. The mixing ventilation system has an almost equal efficiency for removing small passive droplets and the nuclei of droplets whose original size was 100 and 80 μm, respectively. For displacement ventilation, although it has high efficiency in removing small passive droplets, it has difficulty in removing the nuclei of large droplets. In the displacement system, small droplets show a two-zonal distribution in the room, but the nuclei of large droplets are subjected to gravitational force and tend to settle in the lower part of the room.

https://journals.sagepub.com/doi/abs/10.1177/1420326X07084290

 

Swoxid Titanium Oxide Nanofibers Destroy Pathogens

Filter 'paper' made from titanium oxide nanowires is capable of trapping pathogens and destroying them with light. This discovery by an EPFL laboratory could be put to use in personal protective equipment, as well as in ventilation and air conditioning systems.

As part of attempts to curtail the COVID-19 pandemic, paper masks are increasingly being made mandatory. Their relative effectiveness is no longer in question, but their widespread use has a number of drawbacks. These include the environmental impact of disposable masks made from layers of non-woven polypropylene plastic microfibers. Moreover, they merely trap pathogens instead of destroying them. "In a hospital setting, these masks are placed in special bins and handled appropriately," says László Forró, head of EPFL's Laboratory of Physics of Complex Matter. "However, their use in the wider world—where they are tossed into open waste bins and even left on the street—can turn them into new sources of contamination."

Researchers in Forró's lab are working on a promising solution to this problem: a membrane made of titanium oxide nanowires, similar in appearance to filter paper but with antibacterial and antiviral properties.

Their material works by using the photocatalytic properties of titanium dioxide. When exposed to ultraviolet radiation, the fibers convert resident moisture into oxidizing agents such as hydrogen peroxide, which have the ability to destroy pathogens. "Since our filter is exceptionally good at absorbing moisture, it can trap droplets that carry viruses and bacteria," says Forró. "This creates a favorable environment for the oxidation process, which is triggered by light."

The researchers' work appears in Advanced Functional Materials and includes experiments that demonstrate the membrane's ability to destroy E. coli, the reference bacterium in biomedical research, and DNA strands in a matter of seconds. Based on these results, the researchers assert—although this remains to be demonstrated experimentally—that the process would be equally successful on a wide range of viruses, including SARS-CoV-2.

Their article also states that manufacturing such membranes would be feasible on a large scale: the laboratory's equipment alone is capable of producing up to 200 m² of filter paper per week, or enough for up to 80,000 masks per month. Moreover, the masks could be sterilized and reused up a thousand times. This would alleviate shortages and substantially reduce the amount of waste created by disposable surgical masks. Finally, the manufacturing process, which involves calcining the titanite nanowires, makes them stable and prevents the risk of nanoparticles being inhaled by the user.

A start-up named Swoxid is already preparing to move the technology out of the lab. "The membranes could also be used in air treatment applications such as ventilation and air conditioning systems as well as in personal protective equipment," says Endre Horváth, the article's lead author and co-founder of Swoxid.

https://phys.org/news/2020-08-titanate-nanowire-mask-pathogens.htm

 

Purdue Researchers Develop Disinfection Aerosol Which is Not a Biohazard

Purdue researchers have developed an airborne disinfection method – using food-coloring dyes – to be applied to the entire body and rooms for sterilization purposes and lowering the risk of infection.

The Purdue team’s disinfection method uses edible materials. The Purdue team presented the technology in July during a COVID-19 virtual conference sponsored by the National Council of Entrepreneurial Tech Transfer.

“Most of the antiviral and antibacterial sprays used for airborne antiviral and antibacterial disinfectants, such as aerosolized hydrogen peroxide, ozone and deep ultraviolet illumination, are a biohazard risk to humans,” said Young Kim, an associate professor of biomedical engineering at Purdue. “Additionally, disinfectants containing titanium dioxide and noble metal nanoparticles pose carcinogenic and cytotoxicity risks.”

Kim also said new methods are needed since transmission of pathogens (viruses and bacteria) often occurs in the air and infection with pathogens is transmitted by an airborne route. The Purdue method might also help in medical settings, where healthcare workers typically are exposed to the disease-causing agents when they take off their personal protective equipment.

The Purdue airborne antiviral phototherapy technique uses small aerosols FDA-approved food coloring dyes to mitigate the risks of airborne transmissions of pathogens. This is referred to as Photodynamic Airborne Cleaner (PAC).   

“We have demonstrated with our novel solution how visible light activation of several FDA-approved food coloring dyes generate singlet oxygen, which can be used to kill airborne pathogens,” Kim said. “In the medical community, it is well known that singlet oxygen is effective to inactivate viruses. We are developing a scalable aerosol generation system for the dyes, allowing uniform fog-like dispersion lingering in the air to minimize wetting and surface staining. In addition, as health care workers are often infected when removing PPE, this technology can be installed in a confined chamber for health care professionals to change PPE in hospital settings.”

The novel photoreactive arrangement can be used in rooms where many people are present at risk of airborne pathogen exposure.

https://www.purdue.edu/newsroom/releases/2020/Q3/new-approach-to-airborne-disinfection-uses-food-coloring-dyes.html

 

Sinopharm Commits to 337 Tons of Meltblowns for Mask Factories in Hong Kong.

Sinopharm Tech Holdings Ltd.  has entered into product sales agreements with a branch of PetroChina Company Limited and TEDA Filters Co., Ltd.to purchase polypropylene meltblown nonwoven fabrics. The signed product sales agreements include the purchase of meltblown fabric from PetroChina Branch and TEDA Filters to the production needs of the group and to fulfill the actual purchase order quantity. The estimated procurement schedule is 337 tons within the next five months, and subsequent procurement may increase on this basis. Based on the estimated procurement schedule of the meltblown fabric, more than 300 million masks can be produced by the end of 2020.

One of the suppliers of the meltblown fabric, the PetroChina Branch, is a branch of PetroChina Company Limited who is the leading company in China's oil and gas industry, with ownership of petroleum resources, and manufacture of its own industrial chain of polypropylene raw material. The other meltblown supplier, TEDA Filters, is a state-owned enterprise.

Both meltblown suppliers have strong background, high product quality and stable output. This cooperation will ensure that the group has a stable source of high-quality core raw materials and is in line with the group's business tenet of strict adherence to quality. The suppliers are able to provide high-quality meltblown fabric to the group with bacterial filtration efficiency and particle filtration efficiency at or above 99% and the finished masks are expected to meet the higher standards of ASTM F2100.

Since the establishment of the group's first production plant through joint venture in mainland China in February 2020, the commercial blueprint of self-owned mask production lines has rapidly spread. This has allowed the group to quickly establish a second joint venture of medical protective products in the mainland. At the same time, the group set up several mask factories in Hong Kong and completed the construction of cleanrooms, production equipment commissioning and realization of large-scale production.

 

Nonwovens Iberica Purchases Meltblown Line for Mask Products

Nonwovens Ibérica will install the first production line in Spain of meltblown nonwovens, the only raw material that exists to manufacture the filtering layer of masks with guarantees. The new high performance meltblown Reifenhäuser Reicofil line will represent a strategic value for the country of Spain in terms of self-supply of essential products, as it will be the first national high-performance producer of meltblown with production capacity for the manufacture of 1.5 billion face masks per year. With this investment, Spain will have the entire supply chain for the manufacture of masks made in the country.

The installation will be carried out during the last quarter of the year, when the only filtering material that has a Bacterial Filtration Efficiency (BEF) of up to 99% without quality fluctuations for Personal Protection Equipment and sanitary equipment will start its production.

"The Spanish industry has to respond to the evident needs left by this pandemic. Nonwovens Ibérica is now committed to a new line of business with which we intend to supply our country, and beyond, with a material of prime necessity," comments Alberto Miralles, the company's Deputy Director.

The company, with over 50 years' history, located in a region with a great textile tradition and more specifically in the town of Muro de Alcoy, plans to increase its staff by 30% in the near future.

Among their clients, there are national and international companies to whom they supply textile articles for household and industrial cleaning, with absorbent wipes and mops being the most manufactured product. It will have a production capacity of around 5,500 tonnes per year.

 

UPA Healthcare Products Investing in Meltblowns for 86 Million Masks Per Year

 

UPA Corp Bhd’s subsidiary, UPA Healthcare Products Sdn Bhd, is venturing into the manufacturing of meltblown nonwoven fabric in an apparent effort to supply the three-ply and surgical face mask markets, according to a report in The Malaysian Reserve.

Total investment for the project is estimated at RM10 million, or about $2.5 million, to be funded through internally generated funds..

Malaysia-based UPA has placed an order with a reputable meltblown technology developer to supply a state-of-the-art production line with the latest technology to produce nonwoven materials meeting required filtration efficiency. The new line will be installed at the group’s existing facility in Seri Kembangan, Selangor and is expected to commence production by the end of November 2020.

Maximum annual production capacity for the fabric is at 600,000 kgs while maximum production capacity for the three-ply mask and surgical face mask is estimated  at 86 million pieces per year for the first phase.

 

UNC Switches from in Person to Remote After 177 COVID Cases

The University of North Carolina at Chapel Hill, one of the largest schools in the country to bring students to campus for in-person teaching, said today (8-17) it will pivot to all-remote instruction for undergraduates after testing showed a pattern of rapid spread of the novel coronavirus.

Officials announced the abrupt change just a week after classes began at the 30,000-student state flagship university. They said 177 cases of the dangerous pathogen had been confirmed among students, out of hundreds tested. Another 349 students were in quarantine, on and off campus, because of possible exposure to the virus, they said.

The remote-teaching order for undergraduate classes will take effect Wednesday, and the university will take steps to allow students to leave campus housing without financial penalty if they wish.

“We understand the concern and frustrations these changes will raise with many students and parents,” UNC-Chapel Hill’s chancellor, Kevin M. Guskiewicz, and provost, Robert A. Blouin, wrote in a statement. “As much as we believe we have worked diligently to help create a healthy and safe campus living and learning environment, we believe the current data presents an untenable situation.”

Clusters of cases had popped up in three residence halls and a fraternity house at UNC-Chapel Hill in the first week of the fall term, sending students into isolation and quarantine rooms and raising faculty worries about how far the dangerous pathogen will spread in the campus community.

One influential administrator, the UNC-Chapel Hill dean of public health, called for a change in approach because she said the in-person method is not working. 

Air Conditioning Unit Purchases Go Hand in Hand with COVID Filtration Opportunities

Applying efficient filters along with new air conditioning system will save many lives. A study in Southern China where air conditioning with no air filter in a restaurant resulted in a number of COVID cases provides the proof.

Roughly 2 billion AC units are now in operation around the world, making space cooling the leading driver of electricity demand in buildings and of new capacity to meet peak power demand. Residential units – one for every five people – account for 68% of total air conditioners.

However, of the 35% of the world’s population living in countries where the average daily temperature is above 25°C, only 10% own an AC unit. Rising living standards, population growth, and more frequent and extreme heatwaves are expected to stimulate unprecedented cooling demand in the next decade. The number of air conditioners installed could increase another two-thirds by 2030.

Many parts of the world experienced record-high temperatures in 2019, and the global average number of cooling degree days was 15% higher than in 2000. The cooling equipment market growth is accelerating, with global sales rising an estimated 10% between 2018 and 2019, mostly in emerging and developing economies.

China currently dominates the market with 40% of global cooling equipment purchases in 2019. However, although more than 500 million units were sold in China in the last decade, relative AC demand rose more quickly in India and Indonesia, with average yearly installations increasing at a rate of more than 15% (India) and 13% (Indonesia).

 

The U.S. and Japan lead the way presently in terms of households with AC.  India, China and some other Asian countries represent the big growth potential.