Three-Layered Masks Most Effective Against Large Respiratory Droplets

Large Droplets Do Split and Penetrate Inefficient Masks

School District of Lancaster PA will Buy 1300 IsokClean HEPA Filters.

West Virginia K-12 Schools Will Receive $800 Million Under Stimulus Pack

London School Children Will Wear Masks

Air Purification Should a be Part of an Effective School Hygiene Strategy

Students Likely to Experience Flu and Cold Outbreaks

Mask May Become Standard in the Future

Pueblo Colorado Contracts with Willdan for $76 Million Upgrade

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Three-Layered Masks Most Effective Against Large Respiratory Droplets

The droplet impacting on the mask surface is recorded at 20,000 frames per second. These time sequence images of droplet impingement on a single-, double-, and triple-layer masks show the total number count of atomized droplets is significantly higher for the single-layer mask in comparison with the double-layer mask, while only a single droplet penetrates through the triple-layer mask. Credit: Basu et al, Science Advances, March 5, 2021

If you are going to buy a face mask to protect yourself and others from COVID-19, make sure it’s a three-layered mask. You might have already heard this recommendation, but researchers have now found an additional reason why three-layered masks are safer than single or double-layered alternatives. 

While this advice was originally based on studies that showed three layers prevented small particles from passing through the mask pores, researchers have now shown that three-layered surgical masks are also most effective at stopping large droplets from a cough or sneeze from getting atomized into smaller droplets. These large cough droplets can penetrate through the single- and double-layer masks and atomize to much smaller droplets, which is particularly crucial since these smaller droplets (often called aerosols) are able to linger in the air for longer periods of time. Researchers studied surgical masks with one, two and three layers to demonstrate this behavior. 

The researchers reported their results in Science Advances on March 5. 

The team notes that single and double-layer masks do provide protection in blocking some of the liquid volume of the original droplet and are significantly better than wearing no mask at all. They hope their findings on ideal mask pore size, material thickness, and layering could be used by manufacturers to produce the most effective masks designs.

 

Large Droplets Do Split and Penetrate Inefficient Masks

We have previously interviewed  Abhishek Saha  of UCSD and learned of the work they have been doing on droplet evaporation and conclusions that viruses in droplets may only temporarily rest on a mask interior before proceeding. More research has now been completed.

Using a droplet generator and a high-speed time-lapse camera, the team of engineers from the University of California San Diego, Indian Institute of Science and University of Toronto found that, counterintuitively, large respiratory droplets containing virus emulating particles (VEPs) actually get atomized when they hit a single-layer mask, and many of these VEPs pass through that layer. Think of it like a water droplet breaking into smaller droplets as it’s being squeezed through a sieve. For a 620 micron droplet—the size of a large droplet from a cough or sneeze—a single-layer surgical mask only restricts about 30 percent of the droplet volume; a double-layer mask performs better, restricting about 91 percent of the droplet volume; while a three layer mask has negligible, nearly zero droplet ejection. This video illustrates the research as well.

“While it is expected that large solid particles in the 500–600-micron range should be stopped by a single-layer mask with average pore size of 30 micron, we are showing that this is not the case for liquid droplets,” said Abhishek Saha, professor of mechanical and aerospace engineering at UC San Diego and a co-author of the paper. “If these larger respiratory droplets have enough velocity, which happens for coughs or sneezes, when they land on a single-layer of this material it gets dispersed and squeezed through the smaller pores in the mask.” 

Schematic diagram of viral load getting trapped inside the mask layer. Droplets and virus are not drawn to scale. Basu et al, Science Advances, March 5, 2021

This is a problem. Droplet physics models have shown that while these large droplets are expected to fall to the ground very quickly due to gravity, these now smaller, 50-80 micron-sized droplets coming through the first and second layer of a mask will linger in the air, where they can spread to people at larger distances. 

The team of engineers— which also includes Professors Swetaprovo Chaudhuri from University of Toronto, and Saptarshi Basu of the Indian Institute of Science— were well-versed in this type of experiment and analysis, though they were used to studying the aerodynamics and physics of droplets for applications including propulsion systems, combustion, or thermal sprays. They turned their attention to respiratory droplet physics last year when the COVID-19 pandemic broke out, and since then, have been studying the transport of these respiratory droplets and their roles in transmission of Covid-19 type diseases. 

“We do droplet impact experiments a lot in our labs,” said Saha. “For this study, a special generator was used to produce a relatively fast-moving droplet. The droplet was then allowed to land on a piece of mask material—that could be a single layer, double, or triple layer, depending on which we’re testing. Simultaneously, we use a high-speed camera to see what happens to the droplet.”

Using the droplet generator, they’re able to alter the size and speed of the droplet to see how that affects the flow of the particle. 

Going forward, the team plans to investigate the role of different mask materials, as well as the effect of damp or wet masks, on particle attrition. 

School District of Lancaster PA will Buy 1300 IsokClean HEPA Filters.

The district is fighting the COVID-19 pandemic by improving ventilation in schools, said facilities director Dennis LaPorte during the board’s committee meeting.

Quote: “What we have learned since the start of this pandemic is that the focus is now on airborne transmission,” he said to the board. “HVAC systems can contribute to the spread of the virus.”

What it means: So far, district staff is keeping the air systems flowing in buildings at all times, is changing filters regularly, and is instructing staff on strategies to increase air movement. The district is in the process of buying 1,300 IsoClean filtration units (portable HEPA filtration systems that create negative pressure environments by cleaning 99.9% of air particles) and 60 Bi-Polar Ionization units for larger spaces (to kill pathogens, viruses and mold); and of providing fans for nonrenovated buildings. Federal Elementary and Secondary School Emergency Relief, or ESSER, funding — to counteract the COVID-19 pandemic — will cover the estimated $7 million expense.

West Virginia K-12 Schools Will Receive $800 Million Under Stimulus Pack

Now that President Joe Biden has signed the stimulus package into law, millions of dollars of funding is expected to flow into West Virginia's education to help deal with the pandemic's impact.

Roughly $800 million of the relief funding are earmarked K-12 schools in the Mountain State. There's just under $200 million to be dedicated for West Virginia's colleges and universities as well.

WVVA spoke with the State School Superintendent W. Clayton Burch about what this money will mean for the education system in the Mountain State.

"We now know that the new normal may include upgrades to HVAC systems. We know the new normal is going to be more support for mental health and more social and emotional (health). We know that thousands upon thousands of children (have) found themselves behind academically during the pandemic and those supports are going to be essential. So these dollars are very much needed for the state of West Virginia."

W. Clayton Burch, State Superintendent of West Virginia Schools

London School Children Will Wear Masks

As children return to classrooms next week, official government guidance recommends primary school pupils need not don face coverings. However, a London council has advised the 56 primaries under its control that masks should be worn by children as young as four. The government says: “The Department for Education are in contact with the local council on that matter.”

In general, data suggests that children up to the age of 18 experience lower rates of Covid-19-related hospitalization and death compared with all other age groups. While all children are susceptible to and can transmit the virus that causes Covid-19, younger children appear to be less susceptible to infection and when infected less likely to spread the disease than older children and adults.

Last week, the government announced plans for the full reopening of schools on March 8th alongside a suite of measures designed to enhance Covid safety – including twice-weekly testing and a recommendation to wear face coverings in classrooms for secondary pupils. The World Health Organization also recommends that only children aged 12 and over should wear a face covering under the same conditions as adults.

Air Purification Should a be Part of an Effective School Hygiene Strategy

Air purifiers provide maximum protection all year long—not just when it’s too cold to open the windows.

A new report published by Harvard T.H. Chan School of Public Health recommends using air purifiers to scrub  viral droplets out of the air. Harvard’s guidance states, “For improving indoor air quality in the classroom, we recommend prioritizing control strategies — ventilation, filtration, supplemental air cleaning — and targeting a combined 4-6 air changes per hour (ACH) for classrooms through any combination of these approaches.”

However, not all purifiers are the same. You’ll want a filter that either meets or exceeds ratings by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). MERV-13 filters meet the bare minimum. However, HEPA filters come with an exceptional filtration quality that beats what most school systems currently have in place.

For instance, AeraMax Pro commercial grade air purifiers use a four-stage filtration process and have True HEPA filters that capture 99.97% of all airborne contaminants, including airborne viruses. These air purifiers for schools also prove effective in reducing airborne concentrations of influenza A (H1N1) aerosol. In lab tests, the virus reduced by 99.9% within only 35 minutes of turning on the AeraMax Pro unit.

 

Students Likely to Experience Flu and Cold Outbreaks

When many students in the United States go back to in-person learning this fall, parents and school administrators may have to contend with an unexpected infectious disease problem: more colds than usual.

That’s at least the caution coming from researchers in Hong Kong, who published a study last week detailing a spike in common colds after students returned to classrooms in the fall, following nearly a year of remote learning. Specifically, the researchers reported almost seven times more large outbreaks of acute upper respiratory infections (involving 20 people or more) compared with those recorded in 2017, 2018 and 2019 combined.

“Normally, we don’t think of them as a real public health challenge,” Benjamin Cowling, one of the study’s authors and an epidemiologist and biostatistician at the University of Hong Kong School of Public Health, said of common colds. But it can be tough to distinguish the symptoms of a cold from those of Covid-19, especially in kids. And if colds start spreading through schools in the United States, children may be sent home until they have been tested for the coronavirus. They may even have to return to remote learning.

Here’s what happened to students abroad, and what it might mean for kids in the United States.

In late January 2020, as the spread of the coronavirus increased, schools in Hong Kong closed and began teaching students remotely. Schools reopened in late May, but then closed again in July through late September because of a surge of cases of Covid-19. During the last week of October, after schools reopened once more, the Hong Kong Centre for Health Protection received reports of a surge in respiratory infections in kindergartens, child care centers, nursery schools, primary schools and secondary schools.

By the end of November, schools had reported 482 outbreaks of the common cold, mostly in children up to and including primary school age. Researchers defined these types of outbreaks (which were classified differently from the 81 larger ones) as at least three students in a class developing two or more symptoms — cough, runny nose, fever or sore throat — within the span of four days.

Some experts think that the spike in cases may have simply been a result of more people paying attention to every cough, sniffle and runny nose last fall. “These children were likely being tested at a far higher rate than would normally occur outside of a pandemic,” said Dr. Ilan Schwartz, an infectious disease physician at the University of Alberta in Canada.

But Dr. Cowling said that the spike in colds that occurred in Hong Kong in the fall seemed much higher than the increase that was seen in years past. “It did seem like there were an unusual number of children in hospital with rhinoviruses,” he said, referring to the viruses that cause most common colds. And the doctors he has spoken with have told him the infections “seemed to be a bit more severe” than usual, too.

In a correspondence published in The Lancet in December, researchers from the United Kingdom noted something similar — cold viruses spiked in adults in the two weeks after children returned to school last fall, emphasizing that children are the primary drivers of transmission of cold viruses to adults.

What could have been going on. At this point, immunologists can only speculate as to why colds surged after schools reopened in Hong Kong.

What really surprised Dr. Cowling was that colds spread despite the strict virus-prevention measures at schools. In Hong Kong, students spend only half a day at school, and they avoid eating lunch together. They also wear masks all day and sit at distanced desks. “Somehow, the common colds were breaking through those measures,” he said.

 

Mask May Become Standard in the Future  

What a difference a year makes. Prior to March of 2020, if you didn’t work in a hospital setting or on a construction site, it’s unlikely you had ever worn a face mask. Now, we own them by the dozens—a grab bag of KN95s and bandanas, surgical masks, and floral-printed fabric coverings. Such is life during a global pandemic. But when the grip of COVID-19 eases, will these shields leave with it?

While experts urge caution, a lucky few are finding their pandemic protocols already easing. On March 8, the US Centers for Disease Control and Prevention published new guidelines that say those who have been fully vaccinated (that’s two weeks after the second Moderna or Pfizer shot, or two weeks after the one-shot Johnson & Johnson vaccine) can see other fully-vaccinated people unmasked and indoors.

Only 32 million Americans—or roughly 9.7 percent of the population—were fully vaccinated as of March 10. But that number will continue to grow in the coming months, especially if the Biden administration fulfills its promise to prepare enough vaccines for every adult by the end of May. From there, reaching that coveted herd immunity will be a matter of distribution (and public acceptance).

Despite these hopeful scenarios, risks remain. New COVID-19 variants continue to pop up in every corner of the globe, which could render current vaccines less effective in fighting off infection. Epidemiologists expect case numbers to continue rising through the spring. And while Anthony Fauci says he will give his daughter “a big hug” when she too is vaccinated, the world-famous immunologist has also made it a point that Americans may need to wear masks until 2022 in order to stay truly safe.

Wearing a mask might have been a novelty for Americans to get used to this past year, but their large-scale use isn’t new. Face coverings have been a popular public health measure in East Asia for more than a century. According to MIT historian Emma J. Teng, “[masks seem] to have arisen with the 1918 influenza pandemic, becoming commonplace first in Japan.” But their use accelerated after a 2002 outbreak of another coronavirus known as SARS. Now, they’re commonplace in countries like China and Korea, too—something people wear as a courtesy to others if they feel sick, or even as a defense against environmental pollution.

Perhaps because SARS never made its way to America on a population-scale, face masks never made their way into American popular culture. It didn’t help that early in the COVID-19 pandemic, many public health officials in the US advised against wearing masks. Only on April 3, 2020, did the CDC recommend cloth face masks as a way to protect other people, if not the wearer themselves.

There were many reasons for not recommending universal mask wearing. At least one was scientifically sound: At the time, there was little evidence to definitively say masks could stop COVID-19 transmission, says Monica Gandhi of the University of California, San Francisco, School of Medicine. In fact, most of what we knew at that point came from research on mannequins—not real live humans.

Pueblo Colorado Contracts with Willdan for $76 Million Upgrade

Willdan Group, Inc. announced that Pueblo County School District 70 (Pueblo D70) has selected Willdan as the design-build lead for facility improvements totaling up to $76 million. This is a progressive design-build contract that will be paid as a series of fees and executed amendments. Pueblo D70 has committed a first fee of $1.4 million to pay for design and pre-construction work up until the execution of the first amendment. Willdan will provide engineering and construction management to update 19 schools and four district buildings.

Willdan helped the Pueblo D70 secure a BEST grant and a voter-approved bond measure which will be used to fund these latest upgrades. A majority of the funds will go toward major mechanical, electrical, and plumbing upgrades, and $6.3 million will be devoted to infection control, COVID-19 mitigation measures, and districtwide security upgrades.

These projects are scheduled to begin in the summer of 2021. Scopes of work include minor to major sitework on parking lots, sidewalks, and drainage; roof replacements and repairs; new windows and doors; and classroom remodels and improvements such as new ceilings or flooring.

“The District took an important step when we created a facility master plan together,” said Tom Brisbin, Willdan’s CEO and Chairman. “We’re pleased to be here now, turning that plan into real projects that will benefit local students and teachers for years to come.”

Willdan began working with Pueblo D70 in 2016 to support the development of a district-wide, 15-year master plan. In 2018, Willdan delivered energy-efficient upgrades to fund core infrastructure needs for the district through an energy performance contract.

Pueblo County School District 70 is located in Pueblo, Colorado. It was consolidated from 34 smaller school districts in 1950 and is the second largest (by geographical size) school district in the state of Colorado. Pueblo D70 educates over 8,000 students from all over Pueblo County.