Find out which masks off the most protection and why
While paper and cloth masks may help control the spread of Covid-19 among the general public, they are certainly not up to par for use in intensive care.
Here, where the risk of infection is at its highest, medical personnel need much higher level personal protective equipment, which can fully protect them from the virus.
The simplest form of face coating is the surgical mask, generally made up of three layers of paper or fabric. They are resistant to droplets such as those caused by coughing or sneezing, but offer little protection against the viral particles themselves, which are only about 100 nanometers in size (one nanometer is one billionth of a meter).
“A mask, which covers the nose and mouth, but doesn’t perfectly fit your face, is really there to be a barrier to any particles that you could expel,” explains Dr. Nikki McCullough, safety manager for 3M, one of the world’s largest respiratory protection providers. “The mask won’t stop you from breathing very small particles.”
Respirators, on the other hand, are designed to fit tightly to the face, so that air cannot escape or escape and require a rigorous adaptation process.
“When you breathe in, all the air passes through the filter media and that filter media has been tested to a performance standard,” says Dr. McCullough. “So you can be sure that if you get a good seal on your face, the respirator is reducing the number of particles you are going to breathe in your lungs.”
The respirators are available in various forms, the simplest are the respirators with face mask with filter (FFP); some are designed to be disposable, while others can be disinfected and reused.
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In the United States, FFP respirators are classified by the National Institute for Occupational Safety and Health (NIOSH) based on the percentage of particles they filter. Therefore, the N95 and N99 masks filter 95% and 99% of the particles respectively, while the N100 devices eliminate 99.97%.
In Europe, respirators are classified slightly differently. The respirators classified FFP1 filter at least 80% of the particles; FFP2s remove at least 94% and FFP3 devices correspond to N100 by filtering at least 99.97%.
In the meantime, similar to an FFP3 mask in terms of effectiveness, but certainly not in appearance, are the helmet-powered air purifiers (PAPR).
“There you have a more complete solution. There is a face shield for the hood and a tube that would connect to a unit on the belt,” says Brian Hovey, marketing director of the leading respirator manufacturer Honeywell Safety.
“That has an engine or an engine that pumps air through a filter: it’s part of a white suit, so it’s a more complete protective solution.”
At the University of Southampton, the engineers developed a PAPR that they are providing to the University of Southampton hospital – 1,000 are already in use.
It is currently undergoing an official assessment and approval process, so it is not yet in use in intensive care or triage, where FFP3 respirators are required. However, two companies are building them and 5,000 have been ordered to staff in other contexts.
The test process involved both a sense of smell test to see if the wearer could detect external odors, and a physical test to check if tiny particles were actually filtered.
“We put one petri dish inside the hood and another outside, and supplied 1,000 liters of air through the filter,” explains Alex Dickinson, associate professor in the university’s scientific research team on bioengineering.
“We incubated them for 24 hours at 37 ° C and then counted how many of these colony forming units were transmitted through the filter and the hood. In our first experiment, we did not see bacterial growth units inside the hood, but ten formed on the control plate outside. “
The British Standards Institute is currently evaluating the device against European standards, after which, it hopes the team can be used more widely in Southampton and elsewhere.
“Your vision is much better and your communication is better, since the patient can see your whole face; your efficiency is much better as you can switch from one patient to another without wearing and removing PPE,” says the consultant and professor of the hospital in respiratory medicine Paul Elkington.
“Once we started launching it, one of the health care workers said to me ‘I felt sore from the nerves on arrival, but now I feel safe.’
Until recently, the respirator market was primarily industrial – manufacturing, construction and the like.
“If we looked six months ago, with full face respirators – FFP2 and FFP3 – the demand from healthcare was very low,” says Dr. McCullough. “They really only used them for tuberculosis, perhaps a case of measles. But now we see that healthcare around the world is using respirators at a much, much higher rate.”
As a result, manufacturers have been working at full speed to increase their ability to meet new demand.
“We have made significant investments in both the capacity building of our existing facilities and in new ones. In particular, in the United States, we have just had our first products coming out at our facility in Smithfield, Rhode Island, and we have hit 500,000 units “beginning of last week,” says Honeywell’s Brian Hovey.
“Likewise, we have increased our build capacity and are starting to manufacture products in Phoenix. These new facilities add approximately 20 million units per month and we are evaluating potential new facilities worldwide.”
McCullough says that 3M is also increasing production, adding more shifts and improving efficiency.
“We can make the same products but faster; we are adding new lines and seeing some small changes to certain products, such as new headbands,” he says.
So the global offer will hold up?
“In the immediate, probably not, unfortunately – the growth we’ve seen has been unprecedented and, depending on how people think of it as a consumer product, demand far outweighs global supply,” says Hovey.
But, he adds, “We are conversing well with governments to prepare for the future and make sure that strategic supplies are adequately provided.
“If – God forbid – another situation like this occurs, collectively we will be able to respond quickly and effectively”.