Coronavirus Technology Solutions
September 30, 2021

School Mask Mandates are Effective

CDC Mask Guidance is a Start but Easy Fit Test Needed

Mask Efficiency Important to Combat Wildfires and Air Pollution

Reducing Hospitalizations from Wildfire Smoke

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School Mask Mandates are Effective

CDC researchers looked at 999 schools in Maricopa and Pima counties in Arizona, where schools started in July. Of those schools, 21% had a mask requirement at the start of the school year, around 30% added a mandate later, and 48% did not mandate masks.

The researchers defined a Covid-19 outbreak as an instance in which a school had at least two confirmed Covid-19 cases among students or staff within a two-week period at least a week after the start of the school year.

Out of the 191 schools that experienced an outbreak between July 15 and August 31, 59.2% did not have a mask mandate in place. In comparison, 8.4% of the schools that had a mask mandate in place at the start of the school year experienced an outbreak, the researchers found.

A second CDC study examined 520 counties throughout the United States and found that counties where school mask mandates were in effect saw smaller increases of pediatric Covid-19 case rates than other counties.

Specifically, from one to seven days before the start of school to seven to 13 days after the start of school, counties with school mask mandates saw an average increase of 16.32 Covid-19 cases per 100,000 children. Other counties, meanwhile, experienced an average increase of 34.85 cases per 100,000 children.

CDC cautioned that, because the study examined only 16.5% of U.S. counties, it may not apply to the entire country.

How effective are masks in general?

Separately, researchers for another study conducted a randomized controlled trial among 340,000 adults in 600 villages in Bangladesh to evaluate the effectiveness of masks in preventing coronavirus transmission.
The study, which is still undergoing peer review, was run by researchers from Yale University, the University of California, Berkeley School of Public Health, and Stanford University.

The researchers distributed masks to people at their homes and in crowded public places, and they involved community and religious leaders in providing information on why mask-wearing was important. They also encouraged village residents to ask anyone not wearing a mask to wear one.

The researchers found that, among villagers randomly assigned to receive the intervention, mask-wearing increased around 30 percentage points, driving a 9% reduction in Covid-19 cases. The quality of masks used mattered, too: In communities where surgical masks rather than cloth masks were promoted, Covid-19 cases fell by 11%.

The benefits were especially significant in people over the age of 50, the researchers found, with Covid-19 rates dropping by 23% among those ages 50 to 60 and by 35% among those over the age of 60. Writing in the New York Times, the researchers said the study "does not suggest that only older people need to wear masks, but rather that widespread community mask wearing reduces Covid-19 risk, especially for older people."

The researchers also tested the filtration provided by different kinds of masks. They found that surgical masks were more effective than cloth masks at preventing virus particles from passing through them—even after the surgical masks had been worn, bunched up in pockets and purses, and washed with soap and water up to 10 times.

Masks with better filtration and fit than surgical masks, such KF94 or KN95 masks, may provide even better filtration, the researchers suggested.  

https://www.advisory.com/daily-briefing/2021/09/27/face-masks

CDC Mask Guidance is a Start but Easy Fit Test Needed

The CDC has published guidance around mask selection to insure a good fit and adequate filtration. The problem is that it requires effort and analysis by the mask purchaser. 

The ASTM standards make it simple by rating filter efficiency and resistance. However, they do not have a fit rating which would make selection easy. 

Arguments against a fit rating is that it cannot be as precise as media efficiency or resistance. However even media efficiency is not absolutely precise. The basis is the assumption that particles are spherical which they are not.

A fit test can be devised which will be as simple as the efficiency test. What is necessary is to create some useful metrics with compromises such as assuming all particles are spheres.

Here is the CDC guidance on mask fit and filtration efficiency.

·         Improve fit to help prevent air (potentially with respiratory droplets containing the virus) from flowing freely around the edges of the mask and instead forcing air to flow through the mask.

·         Improve filtration to cause more respiratory droplets containing the virus to be captured by the mask.

How to Improve Fit

COVID-19 spreads mainly from person to person through respiratory droplets that come out of the nose and mouth when people breathe, cough, sneeze, talk, shout, or sing. These respiratory droplets travel in the air and can then land in the noses and mouths of others, which spreads COVID-19. Therefore, in order to be effective, masks must always be worn over the nose and mouth.

Ensuring that masks fit well on the face is very important to help prevent getting and spreading COVID-19. A common problem with some masks is that there can sometimes be gaps between the mask and the mask wearer’s face. When there are gaps, air with respiratory droplets containing the virus can leak in and out around the edges of the mask (on the top or the sides). To help prevent air leakage, masks should fit snugly against the sides of the face and not have gaps.

Options to Improve Mask Fit

Nose Wires: Use cloth or medical procedure masks that have a nose wire (a metal strip along the top of the mask) to help prevent air leakage at the top of the mask. Nose wires can also help to prevent fogging of eyeglasses. To get a good fit, make sure to bend the nose wire over your nose to conform to your face.

Mask Fitters and Braces: These devices can be used over a medical procedure mask or a cloth mask to improve the fit by helping to reduce air leakage from around the edges of the mask.

Knotting and Tucking: This technique can be used to improve the fit of a medical procedure mask. Knot the ear loops of the mask where they join the edge of the mask, then fold and tuck the unneeded material under the edges.

How to Check Mask Fit

·         Check for gaps by cupping your hands around the outside edges of the mask. Make sure no air is flowing from the area near your eyes or from the sides of the mask.

·         If the mask has a good fit, you will feel warm air come through the front of the mask and may be able to see the mask material move in and out with each breath.

Other things to consider

Certain types of facial hair, like beards, can make mask fitting difficult. People with beards can do one or more of the following:

·         Shave their beards.

·         Trim their beards close to the face.

·         Use a mask fitter or brace.

·         Wear one disposable mask underneath a cloth mask that has multiple layers of fabric. The second mask should push the edges of the inner mask snugly against the face and beard.

Masks designed for people with beards are being evaluated, and information will be provided when it becomes available.

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How to Improve Filtration

Another important step to increase the protection offered by your mask is to improve filtration. Masks capture respiratory droplets containing the virus when the wearer breathes out, blocking them from reaching the outside air and protecting others. They also serve as a barrier to protect the wearer by capturing respiratory droplets containing the virus breathed out by others, so that the wearer does not breathe them in. A mask with improved filtration will stop more respiratory droplets containing the virus from getting inside your mask if others are sick or escaping from your mask if you are sick.

Layering

Adding more layers of material to a mask (layering) is a good way to reduce the number of respiratory droplets containing the virus that come through the mask. One layering strategy is to use a cloth mask that has multiple layers of fabric. Another strategy is to wear two masks.

Improve Mask Fit and Filtration by Wearing Two Masks

Wearing a second mask on top of a first mask can

·         Improve fit by pressing the inner mask closer to the face, thereby reducing the amount of air that leaks around the edges of the masks.

·         Improve filtration by adding more layers of material to reduce the number of respiratory droplets containing the virus that come through the masks.

One way to do this is to wear a medical procedure mask underneath a cloth mask. A recent study conducted in a laboratory found that this combination provided much better protection to the wearer and to others as compared with a cloth mask by itself or a medical procedure mask by itself.

However, there are some mask combinations that should not be used

·         Do not combine two medical procedure masks. Medical procedure masks are not designed to fit tightly and wearing a second medical procedure mask on top of the first medical procedure mask does not help to improve the fit.

·         Do not combine a KN95 mask with any other masks. You should only use one KN95 mask at a time, and you should not use any type of second mask on top of or underneath a KN95 mask.

Things to Watch Out for When Improving Mask Fit and Filtration

Take into account the following considerations when improving mask fit and filtration:

Ensure the following

·         Breathing is not difficult

o    Breathing might take more effort when wearing a mask that fits and filters better. For example, it might require more effort to breathe when wearing two masks.

·         Vision is not obstructed

o    Adding an extra layer or mask could block vision. Reduced vision could lead to trips, falls, or other injuries.

Try it at home first

·         Try out any potential techniques for improved mask fit and filtration at home before trying it out in public. For example, try walking around the house or outside for several minutes while wearing a mask with improved fit and filtration to assure that you can breathe comfortably and that your vision is not reduced.

Special considerations for children who may have difficulties with techniques for improved fit and filtration

·         Children younger than 2 should not wear any masks.

·         Children 2 and older should always wear masks in a public setting or when they are around people who do not live with them.

·         Some children (age 2 and older) may tolerate wearing one mask without any problems but may not be able to tolerate improved fit and filtration techniques.

Choosing a Mask for Different Situations

Some situations may have higher risk of exposure to COVID-19 than others, so the level of protection needed may vary.

In many circumstances, cloth masks or medical procedure masks work well for community use.

Examples might include:

·         Talking with neighbors when you are outdoors and are at least six feet away

·         Going to a park, as long as you are able to stay at least six feet away from people who do not live with you

For situations when you are in close contact with people who do not live with you, a mask option that provides a higher level of protection (improved fit and/or improved filtration) should be considered.

These situations might include

·         Going to the grocery store

·         Visiting the doctor

·         Working at a job where you are exposed to people who do not live with you and you are not always able to maintain at least six feet of distance from others

One example of an option to improve fit is to use a mask fitter or brace over a medical procedure mask or a cloth mask (as described above) in order to reduce leakage of air around the edges of the mask. Another example of an option that can improve fit and filtration is to wear two masks, which can be done by wearing a cloth mask over a medical procedure mask.

For some situations, especially those that require prolonged close contact with people who do not live with you, you may prefer to use a KN95 mask identified on the FDA Emergency Use Authorization Listexternal icon.

These situations might include

·         Riding on planes, buses, trains, or other forms of public transportation, especially when you are not able to maintain at least 6 feet of distance from other people who do not live with you

·         Taking care of someone who is sick with COVID-19

·         Working at a job where you interact with large numbers of the public, especially if you work in areas with high levels of community transmission. Examples of jobs might include bus drivers and grocery store workers

People at increased risk for severe illness from COVID-19, such as older adults or people with certain underlying medical conditions, may prefer to use a KN95 mask when interacting with people who do not live with them.

A KN95 mask might not always be available when you wish to have a higher level of protection, or you may not be able to properly fit or tolerate a KN95 mask. In that case, you can use a mask fitter or brace over a medical procedure mask or a cloth mask to improve fit. Another option is to improve fit and filtration by wearing two masks to increase protection.

Mask Efficiency Important to Combat Wildfires and Air Pollution

N95 respirators offer the best protection against wildfire smoke and other types of air pollution, performing better than synthetic, cotton and surgical masks.

Researchers performed lab experiments to investigate the ability of different face masks and respirators to filter out particles in a range of sizes found in smoke and air pollution. They placed the different mask materials over a pipe that "breathes" in air and particles inside a plastic box.

N95s were so effective in the lab experiments that the researchers estimate their widespread use could reduce hospital visits attributable to wildfire smoke by 22% to 39%. The study's findings can provide evidence-based recommendations to help people protect themselves during wildfire season.

The new study was published in GeoHealth, AGU's journal investigating the intersection of human and planetary health for a sustainable future.

Climate change has made wildfires more frequent and intense in the Western U.S., and the resulting smoke exposure is taking a toll on people's health. Wildfire smoke contains tiny particles smaller than 2.5 microns in diameter (PM2.5)—about the size of a single bacterium—that enter the lungs and are linked to multiple health problems, including a higher risk of asthma, respiratory infections and chronic obstructive pulmonary disease (COPD).

Face coverings have become second nature to many people during the coronavirus pandemic, making some wonder if masks and respirators could also protect against smoke and pollution. By definition, respirators are tight-fitting protective equipment that seal around the nose and mouth to filter the air coming in and out. Surgical-style face masks are designed to capture the droplets and particles produced by the wearer to prevent the spread of disease.

Researchers compared how much protection different mask types provided from smoke and other aerosols. N95 masks provided the best protection.

"People were asking, should we keep them on in the summer when the fire season starts?" said Jack Kodros, an atmospheric scientist at Colorado State University and lead author on the new study. "There weren't a lot of guidelines on what sort of masks would be helpful for wildfire smoke."

Kodros and his team measured how well N95 respirators and synthetic, cotton and surgical masks each filter out the sizes of particles found in air pollution. Then they calculated how much each face covering would reduce exposure to pollution by considering their ability to filter the particles, and how much air the masks are likely to leak when attached to a person's face.

They found that N95s offer the best protection against wildfire smoke, reducing a person's exposure by a factor of 16. Synthetic and cotton masks do a poor job of filtering out the particle sizes found in wildfire smoke, and only reduced exposure by a factor of 2.2 and 1.4, respectively. Surgical masks filter more than 90% of the particles but previous research has shown they let about 50% of the air leak around the mask, making them only about as effective as the synthetic and cotton options.

N95s also worked best against larger dust particles and urban air pollution, which contains particles from car exhaust that are even smaller than particles from wildfire smoke.

Reducing Hospitalizations from Wildfire Smoke

In the second part of their study, the researchers estimated the benefits of mask wearing across an entire population. They developed a model that took into account the percentage of people likely to wear masks and how consistently they would wear them. They applied the model to the 2012 Washington state fire season to see if mask wearing would have changed the number of hospitalizations due to respiratory problems.

The model suggested that N95s would have prevented about 30% of the hospital visits from wildfire smoke. Surgical masks and synthetic masks would have reduced visits by about 17% and 13%, respectively, while cotton masks would have caused only a 6% reduction.

Kodros emphasizes that these mask recommendations are specific to air pollution and do not apply to the coronavirus. "For COVID-19, you're wearing a mask to protect yourself and also to reduce your own emitted droplets," he said. Fabric masks have been shown to be effective for public health during the current crisis and the Centers for Disease Control and Prevention (CDC) recommends the use of masks with two or more layers of fabric that fit snugly over the nose and mouth.

Stephanie Holm, a pediatrician, environmental epidemiologist and co-director of the Western States Pediatric Environmental Health Specialty Unit at the University of California, San Francisco, says that currently there is a lot of interest—but also a lot of confusion—about how well different mask materials filter out particles. "I think this particular study fills a nice gap in terms of thinking about how we translate that kind of filtration data into real levels of protection, and real differences in health effects that we could see in a population," she said.

Holm was not involved in the study, but she frequently advises families on how to protect themselves from wildfire smoke and is excited to incorporate this information into her recommendations.

https://phys.org/news/2021-09-n95-respirators-robust-wildfire.html