Coronavirus
Technology Solutions
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 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
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
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.
.
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.
·
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.
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
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