Image credit: Physics of Fluids
“A pair of trajectories with and without inertia that start at the same point,” the journal article states. “This is for a particle of diameter 20 μm. The fabric is shown in white, and trajectories with and without inertia are traced out by purple and by orange spheres, respectively. The sphere at the collision point is shown at the true particle size, others along the path are smaller, for clarity. Note that with inertia, the particle penetrates the fabric, while without it, the particle collides at the point shown by the large orange sphere. Here, inertia carries the particle a little farther out from the side of the inter-yarn pore, avoiding a collision. Image produced with ParaView.”
The authors’ findings were recently shared by the popular British website The Daily Mail.
“Cloth masks do little to prevent the spread of COVID-19, or other airborne diseases, a new study finds,” the Mail notes. “Researchers from the University of Bristol in the United Kingdom found that 90 percent of particles could get through cloth masks, making them effectively useless during the pandemic.”
“Cloth masks have been popular in the U.S., as they are easily reusable after washing and at some points were the most accessible due to shortages and high prices for surgical or N95 masks,” the article added.
It is important to note that this study is not saying that cloth masks will stop 10% of Covid case transmission; nor it is saying that they will lower Covid cases by 10% in the aggregate. It is saying that 90% of particles the size of a virus penetrate cloth masks. This means that over time a virus stands a very high chance of mask penetration.
The Wall Street Journal in January also showed that cloth masks are virtually useless, while showing that surgical masks are also ill-equipped to guard against airborne viruses such as Covid-19.
It always important to quantify claims in the medical field. A dishonest researcher can claim that surgical masks are “better” than cloth masks, when the truth is that neither offer serious protection against Covid-19. (See the chart above for estimated time to Covid-19 penetration of various masks.)
“If you really want no exposure, you have to wear the right type of mask,” Monica Gandhi, an infectious disease specialist at the University of California, San Francisco, told WSJ.
“If everyone is just wearing a cloth mask or just a surgical mask, it won’t make any difference” with this highly-transmissible variant, she advised.
Dr. Scott Gottlieb, the former FDA chief who quickly transitioned after leaving office to become a Pfizer board member, has made an admission about cloth masks that should make Americans question the “science” they have been told was unquestionable all along.
Gottlieb appeared on CBS’s “Face the Nation” with host Margaret Brennan and punctured the widespread belief that cloth masks provide any significant protection from airborne respiratory viruses, such as Covid-19.
“Cloth masks aren’t going to provide a lot of protection, that’s the bottom line,” he said. “This is an airborne illness. We now understand that. And a cloth mask is not going to protect you from a virus that spreads through airborne transmission. It could protect better through droplet transmission, something like the flu, but not this coronavirus.”
Dr. Leanna Wen, a CNN health analyst, also revealed the facts about masks on the network.
“Don’t wear a cloth mask,” she said. “Cloth masks are little more than facial decorations. There’s no place for them in light of Omicron.”
In January 2021, CDC Director Walensky explained why the general public should not wear N95 masks for long hours over the course of a day.
“They’re very hard to breathe in when you wear them properly,” Walensky said. “They’re very hard to tolerate when you wear them for long periods of time.”
It’s important to note that the health experts knew that cloth masks were ineffective all along, but recommended them anyway. It is not just the Omicron variant that the masks don’t stop, but all Covid-19 variants. This has not only been shown repeatedly in terms of international and state-level comparative data, but a Physics of Fluid article published in July 2021 stated as much.
“A total of seven PPE configurations were considered, with the manikin fitted with (i) no mask, (ii) an unvalved KN95 mask, (iii) a typical three-ply blue pseudo-surgical mask, (iv) a three-ply cotton cloth non-medical mask, (v) a 3M R95 particulate respirator (equivalent to N95 for human borne aerosols), (vi) an unvalved KN95 mask with 3 mm gaps around cheeks and nose, and (vii) a KN95 mask with a single one-way valve on the left side,” the physicists stated. “The parameters presented in Table I were kept constant across all cases.”
“Tests characterizing breath particle concentration, breath volume, and ideal mask filtration efficiency were also performed,” the authors noted.
Image credit: Physics of Fluids
The filtration efficiency rates are provided below.
“The results… show that the KN95 and cloth masks have the highest pressure drops and resistance coefficients, indicating relatively poor breathability,” the authors conclude. “In comparison, the pressure drop across the R95 mask is approximately 40% lower than that of the KN95 mask, which is significant given a similar level of filtration efficiency. Pressure drop across the surgical mask is comparable to that of the R95, indicating a similar level of breathability and comfort; however, this comes at the cost of significantly reduced filtration efficiency.”
“It should be noted that substantial variability in measured pressure drop can occur even for the same mask types from different manufacturers… however, the trends observed in the present measurements fall within the range of values reported previously,” the authors add. “Therefore, these results can serve as a qualitative guide toward the balance between ideal filtration performance and breathability for common face masks.”
(TLB) published this article from Becker News as written and compiled by Kyle Becker
Header featured image (edited) credit: Mask/Shutterstock
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