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What is the best mask for COVID-19? A mechanical engineer explains the science after 2 years of testing masks in his lab

Photo: Adobe Stock

1. What changed in the CDC guidelines?

The CDC currently recommends that you “wear the most protective mask you can that fits well and that you will wear consistently.” The question, then, is what type of mask offers the best protection for you – by filtering the air you breathe in – and for those around you – by filtering the air you breathe out?

The CDC’s updated guidelines clearly lay out the hierarchy of protection: “Loosely woven cloth products provide the least protection, layered finely woven products offer more protection, well-fitting disposable surgical masks and KN95s offer even more protection, and well-fitting NIOSH-approved respirators (including N95s) offer the highest level of protection.”

From a performance standpoint, the N95 and KN95 masks are the best option. While supply chain limitations led to the CDC recommending people not wear N95s early in the pandemic, today they are easily obtainable and should be your first choice if you want the most protection.

The biggest change in the new guidelines has to do with cloth masks. Previous guidance from the CDC had said that some cloth masks could offer acceptable levels of protection. The new guidance still acknowledges that cloth masks can offer a small amount of protection but places them at the very bottom of the bunch.

N95 masks are made from a tangled web of tiny plastic fibers that are very effective at trapping particles. Alexander Klepnev via Wikimedia CommonsCC BY-SA

2. What’s the difference between N95, surgical and cloth mask materials?

The effectiveness of a mask – how much protection a mask provides the wearer – is a combination of two major elements. First, there’s the ability of the material to capture particles. The second factor is the fraction of inhaled or exhaled air leaking out from around the mask – essentially, how well a mask fits. 

Most mask materials can be thought of as a tangled net of small fibers. Particles passing through a mask are stopped when they physically touch one of those fibers. N95s, KN95s and surgical masks are purpose-built to be effective at removing particles from air. Their fibers are typically made from melt-blown plastics, often polypropylene, and the strands are tiny – often less than four thousandths of an inch (10 micrometers) in diameter – or approximately one third the width of a human hair. These small fibers create a large amount of surface area within the mask for filtering and collecting particles. Although the specific construction and thickness of the materials used in N95, KN95 and surgical masks can vary, the filter media used are often quite similar.

These fibers are very tightly packed together so the gaps a particle must navigate through are very small. This results in a high probability that particles will end up touching and sticking to a fiber as they pass through a mask. These polypropylene materials also often have a static charge that can help attract and catch particles. 

Cloth masks are typically made of common woven materials such as cotton or polyester. The fibers are often large and less densely packed together, meaning particles can easily pass through the material. Adding more layers can help, but stacking layers has a diminishing return and the performance of a cloth mask, even with multiple layers, will still typically not match that of surgical mask or N95.

3. How much does fit matter for masks?

Fit is the other major component in how effective a mask is. Even if the materials used in a mask were perfect and it removed all particles from the air that passed through it, a mask can offer protection only if it doesn’t leak.

When you breathe in and out, air will always take the path of least resistance. If there are any gaps between a mask and someone’s face, a substantial fraction of every breath will seep out through those gaps and the mask will provide relatively little protection

Many cloth mask designs simply do not seal well. They are not stiff enough to push against the face, there are gaps where the mask doesn’t even come in contact with the face and it is not possible to cinch them tightly enough against the skin to form a decent seal.

But leaking is a concern for all masks. Although the materials used in surgical masks are quite effective, they often bunch and fold on the sides. These gaps provide an easy route for air and particles to leak out. Knotting and tucking surgical masks or wearing a cloth mask over a surgical mask can both significantly reduce leakage.

N95 masks aren’t immune to this problem either; if the nose clip isn’t securely pushed against your face, the mask is leaking. What makes N95s unique is that a specific requirement of the N95 certification process is making sure the masks can form a good seal.

4. What is different about omicron?

The mechanics of how masks function is likely no different for omicron than any other variant. The difference is that the omicron variant is more easily transmitted than previous variants. This high level of infectiousness makes wearing good-quality masks and wearing them correctly to limit the chances of catching or spreading the coronavirus that much more critical.

Unfortunately, the attributes that make for a good mask are the very things that make masks uncomfortable and not very stylish. If your cloth mask is comfy and light and feels like you are wearing nothing at all, it probably isn’t doing much to keep you and others safe from the coronavirus. The protection offered by a high-quality, well-fitting N95 or KN95 is the best. Surgical masks can be very effective at filtering out particles, but getting them to fit correctly can be tricky and makes the overall protection they will provide you questionable. If you have other options, cloth masks should be a last choice.

Originally published on The Conversation by Christian L’Orange and republished under a Creative Commons License

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US Denounced as ‘Biggest Peddler of Financial Secrecy’ After Pandora Papers Leak

Above:Photo Collage / Lynxotic / Original Image by ICIJ

“U.S. President Biden must match his own rhetoric on shutting down global illicit finance, and start with the biggest offender—his own country.”

The leak of an enormous trove of tax haven files over the weekend offered a further glimpse into the secretive world of offshore finance—a system facilitated by the U.S. and other rich nations—and prompted calls for immediate changes to global rules that let the powerful hide their wealth, skirt their obligations, and starve governments of crucial revenue.

“This is where our missing hospitals are,” Susana Ruiz, the tax policy lead at Oxfam International, said in a statement. “This is where the pay-packets sit of all the extra teachers and firefighters and public servants we need. Whenever a politician or business leader claims there is ‘no money’ to pay for climate damage and innovation, for more and better jobs, for a fair post-Covid recovery, for more overseas aid, they know where to look.”

“Tax havens cost governments around the world $427 billion each year,” Ruiz added. “That is the equivalent of a nurse’s yearly salary every second of every hour, every day. Ordinary taxpayers have to pick up the pieces. Developing countries are being hardest hit, proportionately. Corporations and the wealthiest individuals that use tax havens are out-competing those who don’t. Tax havens also help crime and corruption to flourish.”

Like the 2016 Panama Papers, the International Consortium of Investigative Journalists’ (ICIJ) Pandora Papers shine additional light on the functioning of a “shadow economy” that world leaders, celebrities, and billionaire business moguls—including some accused of egregious crimes—are exploiting to shield trillions of dollars in assets from transparency and taxation.

The 11.9 million files obtained, analyzed, and leaked by the ICIJ reveal the closely-guarded financial maneuverings of more than 330 politicians and top public officials from nearly 100 countries and territories, including dozens of current national leaders.

“The secret documents expose offshore dealings of the King of Jordan, the presidents of Ukraine, Kenya, and Ecuador, the prime minister of the Czech Republic, and former British Prime Minister Tony Blair,” ICIJ notes in a summary of its sprawling cache of documents. “The files also detail financial activities of Russian President Vladimir Putin’s ‘unofficial minister of propaganda’ and more than 130 billionaires from Russia, the United States, Turkey, and other nations.”

The trove also links prominent athletes, models, and artists to offshore assets, including India’s famous cricketer Sachin Tendulkar, pop music star Shakira, and supermodel Claudia Schiffer.

But Alex Cobham, chief executive of the Tax Justice Network, cautioned that a narrow focus on the individuals who have made use of an international tax system rigged in their favor diverts attention from the institutions and countries that have done the rigging.

“These personal actions are shameful and will no doubt come under great scrutiny in the coming days, but it’s important that we don’t lose sight of one crucial fact: few of the individuals had any role in turning the global tax system into an ATM for the superrich,” Cobham wrote in a blog post on Sunday. “That honor goes to the professional enablers—banks, law firms, and accountants—and the countries that facilitate them.”

Cobham observed that the Pandora Papers—the product of a nearly two-year investigation by more than 600 journalists in 117 countries and territories—confirm that the United States is “the world’s biggest peddler of financial secrecy.”

“The biggest blockers to transparency are the U.S. … and the U.K., the leader of the world’s biggest tax haven network,” Cobham wrote. “We need full transparency so we can hold tax abusers accountable, especially when our politicians are among them. U.S. President Biden must match his own rhetoric on shutting down global illicit finance, and start with the biggest offender—his own country.”

As the ICIJ notes, the new files show in some detail “how the United States, in particular, has become an increasingly attractive destination for hidden wealth, although the U.S. and its Western allies condemn smaller countries for allowing the flow of money and assets tied to corruption and crime.”

“The Pandora Papers include documents from 206 U.S. trusts in 15 states and Washington, D.C., and 22 U.S. trustee companies,” the ICIJ points out. “The documents provide details about the movement of hundreds of millions of dollars from offshore havens in the Caribbean and Europe into South Dakota, a sparsely populated American state that has become a major destination for foreign money.”

“We in the U.S. should be embarrassed that we’ve become a magnet for kleptocratic funds,” said Chuck Collins, director of the Program on Inequality and the Common Good at the Institute for Policy Studies.

Conspicuously absent from the Pandora Papers is any mention of the wealthiest people in the U.S., including Bill Gates, Elon Musk, Warren Buffett, and Jeff Bezos—the richest man in the world. But as the Washington Post explains, that could be because “the uber-rich in the United States tend to pay such low tax rates that they have less incentive to seek offshore havens.”

In response to the Pandora Papers revelations, Oxfam called on world governments to crack down on tax havens by taking a number of steps, including:

  1. Ending tax secrecy on individuals, offshores, and multinational corporations. Set up a public register on the real owners of bank accounts, trusts, shell companies, and assets. Require multinational corporations to publicly report their accounts where they do business, country-by-country.
  2. Increasing the use of automatic exchange, allowing revenue authorities access to information they need to track the money.
  3. Ending corporate profit shifting to tax havens via new rules, and by setting a global minimum tax under the OECD’s BEPS deal, ideally of around 25%.
  4. Agreeing a global blacklist of tax havens and taking counter measures, including sanctions, to limit their use.
  5. Setting a new global agenda on taxing wealth and capital fairly; addressing tax competition between countries on high-net-worth-individuals, either on income or wealth, against agreed standards.

“Governments’ promises to end tax havens are still a long way from being realized,” said Ruiz. “We cannot allow tax havens to continue to stretch global inequality to breaking point while the world experiences the largest increase in extreme poverty in decades.”

Originally published on Common Dreams by JAKE JOHNSON and republished under a Creative Commons License (CC BY-NC-ND 3.0).

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