Coronavirus
Technology Solutions
Don’t Confuse Medical with Public Health
Guidance Mask and Filter Protection are Part of a Swiss Cheese Defense Program
Clean Air is the Goal for Hotels and Cruise
Lines
Michael Mina
of Harvard says it is
important
to distinguish medical from public
health guidance. This is good
advice. In fact it is important to also
distinguish guidance for vaccine manufacture.
It is also desirable to distinguish between sub
segments. The guidance for personnel entering an
isolation unit are far different than for a
person at the registration desk in a hospital.
The efficiency needs can be achieved with a
combination of filters and masks. If there are
filter cubes on the city streets at
intersections the need for more efficient masks
is less. If the elevator has a HEPA filter and
laminar air flow there is less of a burden on
the mask. This combination of filters can be
conceived as the swiss cheese defense program as
explained below.
This concept was the basis of an article by Siobhan
Roberts
published Dec. 5, 2020
in the NY Times. Lately, in the ongoing
conversation about how to defeat the coronavirus,
experts have made reference to the “Swiss cheese
model” of pandemic defense. The metaphor is easy enough to grasp: Multiple layers of protection, imagined as cheese slices, block the spread of the new coronavirus, SARS-CoV-2, the virus that causes Covid-19. No one layer is perfect; each has holes, and when the holes align, the risk of infection increases. But several layers combined — social distancing, plus masks, plus hand-washing, plus testing and tracing, plus ventilation, plus government messaging — significantly reduce the overall risk. Vaccination will add one more protective layer.
“Pretty soon you’ve created an impenetrable
barrier, and you really can quench the
transmission of the virus,” said Dr. Julie
Gerberding, executive vice president and chief
patient officer at Merck, who recently
referenced the Swiss cheese model when speaking
at a virtual gala fund-raiser for MoMath, the
National Museum of Mathematics in Manhattan.
“But it requires all of those things, not just
one of those things,” she added. “I think that’s
what our population is having trouble getting
their head around. We want to believe that there
is going to come this magic day when suddenly
300 million doses of vaccine will be available
and we can go back to work and things will
return to normal. That is absolutely not going
to happen fast.”
Rather, Dr. Gerberding said in a follow-up
email, expect to see “a gradual improvement in
protection, first among the highest need groups,
and then more gradually among the rest of us.”
Until vaccines are widely available and taken,
she said, “we will need to continue masks and
other common-sense measures to protect ourselves
and others.”
In October, Bill Hanage, an epidemiologist at
the Harvard T.H. Chan School of Public Health,
retweeted an infographic rendering
of the Swiss cheese model, noting that it
included “things
that are personal *and* collective
responsibility — note the ‘misinformation mouse’
busy eating new holes for the virus to pass
through.”
“One
of the first principles of pandemic response is,
or ought to be, clear and consistent messaging
from trusted sources,” Dr. Hanage said in an
email. “Unfortunately the independence of
established authorities like the C.D.C. has been
called into question, and trust needs to be
rebuilt as a matter of urgency.” A catchy
infographic is a powerful message, he said, but
ultimately requires higher-level support.
The Swiss cheese concept originated with James
T. Reason, a cognitive psychologist, now a
professor emeritus at the University of
Manchester, England, in his 1990 book, “Human
Error.”
A succession of disasters including
the Challenger shuttle explosion, Bhopal and
Chernobyl — motivated the concept, and it became
known as the “Swiss cheese model of accidents,”
with the holes in the cheese slices
representing errors that
accumulate and lead to adverse events.
The model has been widely used by safety
analysts in various industries, including
medicine and aviation, for many years. (Dr.
Reason did not devise the “Swiss cheese” label;
that is attributed to Rob Lee, an Australian
air-safety expert, in the 1990s.) The model
became famous, but it was not accepted
uncritically; Dr. Reason himself noted that it
had limitations and was intended as a generic
tool or guide. In 2004, at a workshop addressing
an aviation accident two years earlier near
Überlingen, Germany, he delivered a talk with
the title, “Überlingen: Is Swiss cheese past
its sell-by date?”
In 2006, a review of the model, published by
the Eurocontrol
Experimental Center, recounted that Dr.
Reason, while writing the book chapter “Latent
errors and system disasters,” in which an early
version of the model appears, was guided by two
notions: “the biological or medical metaphor of
pathogens, and the central role played by
defenses, barriers, controls and safeguards
(analogous to the body’s autoimmune system).”
The cheese metaphor now pairs fairly well with
the coronavirus pandemic. Ian M. Mackay, a
virologist at the University of Queensland, in
Brisbane, Australia, saw a smaller version on Twitter,
but thought that it could do with more slices,
more information. He created, with
collaborators, the “Swiss
Cheese Respiratory Pandemic Defense” and
engaged his Twitter community, asking for
feedback and putting the visualization through
many iterations. “Community engagement is very
high!” he said. Now circulating widely, the
infographic has been translated into
more than two dozen languages. “This multilayered approach
to reducing risk is used in many industries,
especially those where failure could be
catastrophic,” Dr. Mackay said, via email.
“Death is catastrophic to families, and for
loved ones, so I thought Professor Reason’s
approach fit in very well during the circulation
of a brand-new, occasionally hidden, sometimes
severe and occasionally deadly respiratory
virus.”
The following is an edited version of a recent
email conversation with Dr. Mackay by the
Washington Post.
Q. What does the Swiss cheese model show?
A. The real power of this infographic — and
James Reason’s approach to account for human
fallibility — is that it’s not really about any
single layer of protection or the order of them,
but about the additive success of using multiple
layers, or cheese slices. Each slice has holes
or failings, and those holes can change in
number and size and location, depending on how
we behave in response to each intervention.
Take masks as one example of a layer. Any mask
will reduce the risk that you will unknowingly
infect those around you, or that you will inhale
enough virus to become infected. But it will be
less effective at protecting you and others if
it doesn’t fit well, if you wear it below your
nose, if it’s only a single piece of cloth, if
the cloth is a loose weave, if it has an
unfiltered valve, if you don’t dispose of it
properly, if you don’t wash it, or if you don’t
sanitize your hands after you touch it. Each of
these are examples of a hole. And that’s in just
one layer.
To be as safe as possible, and to keep those
around you safe, it’s important to use more
slices to prevent those volatile holes from
aligning and letting virus through.
Q. What have we learned since March?
A. Distance is the most effective intervention;
the virus doesn’t have legs, so if you are
physically distant from people, you avoid direct
contact and droplets. Then you have to consider
inside spaces, which are especially in play
during winter or in hotter countries during
summer: the bus, the gym, the office, the bar or
the restaurant. That’s because we know
SARS-CoV-2 can remain infectious in aerosols
(small floaty droplets) and we know that aerosol
spread explains Covid-19 superspreading events.
Try not to be in those spaces with others, but
if you have to be, minimize your time there
(work from home if you can) and wear a mask.
Don’t go grocery shopping as often. Hold off on
going out, parties, gatherings. You can do these
things later.
Q. Where does the “misinformation mouse” fit in?
A. The misinformation mouse can erode any of
those layers. People who are uncertain about an
intervention may be swayed by a loud and
confident-sounding voice proclaiming that a
particular layer is ineffective. Usually, that
voice is not an expert on the subject at all.
When you look to the experts — usually to your
local public health authorities or the World
Health Organization — you’ll find reliable
information.
An effect doesn’t have to be perfect to reduce
your risk and the risk to those around you. We
need to remember that we’re all part of a
society, and if we each do our part, we can keep
each other safer, which pays off for us as well.
Another example: We look both ways for oncoming
traffic before crossing a road. This reduces our
risk of being hit by a car but doesn’t reduce it
to zero. A speeding car could still come out of
nowhere. But if we also cross with the lights,
and keep looking as we walk, and don’t stare at
our phone, we drastically reduce our risk of
being hit.
We’re already used to doing that. When we listen
to the loud nonexperts who have no experience in
protecting our health and safety, we are
inviting them to have an impact in our lives.
That’s not a risk we should take. We just need
to get used to these new risk-reduction steps
for today’s new risk — a respiratory virus
pandemic, instead of a car.
Q. What is our individual responsibility?
A. We each need to do our part: stay apart from
others, wear a mask when we can’t, think about
our surroundings, for example. But we can also
expect our leadership to be working to create
the circumstances for us to be safe — like
regulations about the air exchange inside public
spaces, creating quarantine and isolation
premises, communicating specifically with us
(not just at us), limiting border travel,
pushing us to keep getting our health checks,
and providing mental health or financial support
for those who suffer or can’t get paid while in
a lockdown.
Q. How can we make the model stick?
A. We each use these approaches in everyday
life. But for the pandemic, this all feels new
and like a lot of extra work. Because everything
is new. In the end, though, we’re just forming
new habits. Like navigating our latest phone’s
operating system or learning how to play that
new console game I got for my birthday. It might
take some time to get across it all, but it’s
worthwhile. In working together to reduce the
risk of infection, we can save lives and improve
health.
And as a bonus, the multilayered risk reduction
approach can even decrease the number of times
we get the flu or a bad chest cold. Also,
sometimes slices sit under a mandate — it’s
important we also abide by those rules and do
what the experts think we should. They’re
looking out for our health.
https://www.nytimes.com/2020/12/05/health/coronavirus-swiss-cheese-infection-mackay.html
Clean Air is the Goal for
Hotels and Cruise Lines
Elaine Glusac covered the activities in this
travel segment in an article in the NY Times
published Dec.
3, 2020.
Her article shows that while HEPA filters
and other reliable air cleaning devices are
being used there is very likely false optimism
about other technologies. When the coronavirus first
hit, hotels quickly adopted enhanced cleaning
polices, including germ-killing electrostatic
spraying and ultraviolet light exposure in guest
rooms and public areas. But as research on virus
spread has shifted focus from surface contact
to airborne
transmission, some hotels and cruise
ships are scrubbing the very air travelers
breathe with a variety of air filtration and
treatment systems. “The best amenity that any
hotel could provide under those circumstances is
safety, especially in the air,” said Carlos
Sarmiento, the general manager of the Hotel
Paso del Norte in El Paso, Texas. The
1912 vintage hotel recently reopened after a
four-year renovation that included installing a
new air purification system called Plasma Air
that emits charged ions intended to neutralize
the virus and make particles easier to filter
out. With the new air-scrubbing
campaigns, hotels are following airlines, many
of which have hospital-grade, high-efficiency
particulate air (HEPA) filters that are said to
be over 99 percent effective in capturing tiny
virus particles, including the coronavirus. Hotels and cruise ships can
more easily ensure social distancing than
airplanes, but, given the recent research on the
importance of enhanced air filtration, some are
adding air-cleaning dimensions to their heating,
ventilation and air conditioning (HVAC) systems,
which already aim to remove dust, smoke, odors
and allergens. Researchers, including those
at New Orleans’s Tulane University, have
found that the tiny aerosol particles
of SARS-CoV-2 that are emitted when someone with
the virus speaks or breathes can remain in the
air for up to 16 hours. Along with social distancing,
mask wearing is the first line of defense
against breathing contaminated air indoors, said
Dr. Philip M. Tierno Jr., a professor of
microbiology and pathology at New York
University School of Medicine, who has consulted
with HVAC companies. “HVAC systems are of great
significance in reducing the amount of airborne
particles since this virus can be spread in an
airborne fashion,” he added, calling the tiniest
aerosols “the most dangerous.”
However, some experts are skeptical,
pointing to evidence that these systems may
introduce ozone or particles that are dangerous
if inhaled. ASHRAE,
a professional society of air-conditioning,
heating and refrigerating engineers, notes that
the technology is still “emerging” and lacks
“scientifically-rigorous, peer-reviewed
studies.” The bipolar ionization company
AtmosAir Solutions provided results of tests
performed by the independent Microchem
Laboratory, which evaluates sanitizing products,
that found the technology reduced the presence
of coronavirus by more than 99 percent within 30
minutes of exposure.
“We talk about it as nature’s cleaning device,”
said Kevin Devlin, the chief executive of
WellAir, which sells the bipolar ionization
system Plasma Air installed at the Hotel Paso
del Norte. He noted that air at high elevations
in the mountains that “smells clean” has higher
amounts of ions.
Some anti-viral HVAC systems feature germicidal
ultraviolet light in the ductwork (the Food and
Drug Administration states that
ultraviolet-C lamps have been shown to
inactivate the virus). Such a system was
installed at The
Distillery Inn in Carbondale, Colo., and
includes a three-hour disinfection cycle between
guests.
Systems often use a combination of these
technologies with efficient air filters that
remove contaminants. Filters with Minimum
Efficiency Reporting Values (MERV) of 13 or
higher are best at capturing the coronavirus,
according to the Environmental
Protection Agency.
According to its website,
the agency “recommends increasing ventilation
with outdoor air and air filtration as important
components of a larger strategy that includes
social distancing, wearing cloth face coverings
or masks, surface cleaning and disinfecting,
handwashing, and other precautions.”
“In a transient environment, like a hotel, motel
or dormitory, you don’t know who was there
before you and what their health was,” said Wes
Davis, the director of technical services with
the Air Conditioning Contractors of America, a
trade association, adding that good housekeeping
is a top priority in such places. “As for the
other items like ultraviolet exposure or
ionization, every little bit helps, but I’m not
quite sure any of them is the perfect solution.
It’s more like a concert.”
Throughout the summer, the Madison
Beach Hotel, part of Hilton’s Curio
Collection of hotels, in Madison, Conn., used
its outdoor spaces for dining and even holding
meetings in tents. But with the approach of cold
weather, HVAC contractors installed an air
purification system that uses UV light and
ionized hydrogen peroxide in most public areas
of the hotel, including the indoor restaurant
and meeting rooms. Spa treatment rooms each have
their own portable air purification systems.
“We wanted to create an environment that was as
safe as possible,” said John Mathers, the
hotel’s general manager, adding that each guest
room has its own closed HVAC system that doesn’t
mingle with others and thus doesn't require
extra purifying. “The air being recirculated in
your room is your air.”
But many hotels are bringing units into the
guest rooms for extra assurance. In Rhode
Island, rooms at the Weekapaug
Inn and Ocean
House hotel, both run by Ocean House
Management, have Molekule air
purifiers that destroy pollutants and viruses at
a rate above 99 percent, according to
the independent testing group Aerosol
Research and Engineering Laboratories.
Larger units were recently added to restaurants
and public spaces, and the portable units have
become a top seller, starting at around $500, in
Ocean House’s gift shop.
Decisions about installing air purification
systems tend to happen at the property or
ownership level, rather than the brand level.
But Hilton has AtmosAir’s bipolar ionization air
purification systems in its Five
Feet to Fitness rooms, more than 100
guest rooms across 35 hotels that double as mini
gyms with weights, indoor cycles and meditation
chairs.
Many hotels have long offered allergy-free or
wellness rooms to travelers that feature
heightened purification systems. Pure Wellness
has its Pure
Room technology that claims to eliminate
viruses, bacteria and fungi, including air filters effective
enough to trap the coronavirus, in over 10,000
rooms worldwide.
The 112-passenger SeaDream I from the SeaDream
Yacht Club took many precautions —
including pre-embarkation Covid-19 testing,
electrostatic fogging of public areas and UV
light sterilization after nightly turndown —
before it launched its winter season from
Barbados on Nov. 7, and still a passenger got
the virus within days of departure, cutting
the trip short. Eventually nine
infections were diagnosed and the line canceled
future 2020 sailings. (The cruise line did not
respond to a requests for comment on whether any
improvement had been made to the ship’s
ventilation system.)
SeaDream’s failed cruise exemplifies the
challenges the entire industry faces. Some
health experts think that upgraded air
filtration could help. Adopting systems that are
“aimed at reducing occupant exposure to
infectious droplets/aerosols,” and upgrading
HVAC systems with MERV 13 filters were among 74
critical recommendations to
ship lines made by the Healthy Sail Panel, a
group of public health experts assembled by
Royal Caribbean Group and Norwegian Cruise Line
Holdings in September.
The Centers for Disease Control and Prevention maintains that
ships remain vulnerable to spreading infection
based on population density and the inability of
crew in particular to maintain social distance
in their work spaces and living quarters. Still,
cruising is expected to resume in U.S. waters
for ships carrying 250 or more passengers and
crew in the first half of 2021, pending
certification under the C.D.C.’s Framework
for Conditional Sailing Order,
which spells out minimum standards for social
distancing, face coverings and hand hygiene, but
does not mention air circulation systems.
Despite the C.D.C.’s lack of emphasis on air
filtration, some cruise companies are upgrading
their ventilation systems, in addition to
designating quarantine areas and reconfiguring
dining rooms.
Norwegian Cruise Line,
for example, has announced its ships will use
HEPA filters. And Princess
Cruises has said it will upgrade its
ships’ HVAC systems to MERV 13 filters, refresh
the air in cabins and public spaces every five
to six minutes, and install HEPA filters in
areas such as medical centers and isolation
rooms.
The new Virgin
Voyages cruise line, whose launch has
been delayed by the pandemic, confirmed it had
installed AtmosAir bipolar ionization systems on
its inaugural ship, the roughly 2,700-passenger
Scarlet Lady, and a second ship coming in 2021.
“This
was a multimillion-dollar investment and based
on our research and growing understanding of the
virus, was an important step to sailing safely,”
wrote Tom McAlpin, the chief executive of Virgin
Voyages, in an email.
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