N95 / FFP2 /FFP3- what do those stand for?
Being professional protection, those respirator shave to comply with certain quality standards in order to make sure they deliver the protection they promise. In Europe, this standard is defined by ISO /CEN/ EN. All those standards define, which filtering capacity one respirator has.
-FFP1 (Filtering Face Piece 1) stops at least 80% of the particles that are 0,3 microns or larger.
-FFP2 (Filtering Face Piece 2) stops at least 95% of the particles that are 0,3 microns or larger.
-FFP3 (Filtering Face Piece 3) stops at least 99% of the particles that are 0,3 microns or larger.
-P1 stops at least 80% of the particles that are 0,3 microns or larger.
-P2 stops at least 94% of the particles that are 0,3 microns or larger.
-P3 stops at least 99,95% of the particles that are 0,3 microns or larger.
In USA there is similar standardisation by NIOSH – part of the Center for Disease Control (CDC). According to those:
-N95 stops at least 95% of the particles that are 0,3 microns or larger.
-N99 stops at least 99% of the particles that are 0,3 microns or larger.
-N100 stops at least 99,97% of the particles that are 0,3 microns or larger.
So, to approximate the things, we can say:
PS: China has their own standard, which approximates to American ones. Those masks carry a sign KN95 and similar.
Here you can find my insta- guide to choosing a mask against Corona:
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How big are the viruses and bacteria and can the medical face masks stop them?
According to this research, Corona virus has a diameter of 60 to 140nm (0,06-0,14Microns)
Diameter varied from about 60 to 140 nm. Virus particles had quite distinctive spikes, about 9 to 12 nm, and gave virions the appearance of a solar corona.
Like we saw earlier, filtering capacity of a mask is measured at 0,3microns, which is more than double the size of the biggest Corona virus!However, the virus does not fly alone. Covid19 virus is within a aerosol that has up to 5micron diameter, or within a droplet that is bigger. But being heavier, droplet should also not be able to float far away so it is less dangerous. So our problem is aerosol drios that are smaller than 5microns. (to be honest, there is a scientific argument going on about how big is the aerosol and how big is the droplet and it gets very weird….so lets keep it simple here and use the WHO standardisation. According to them, up to 5microns is aerosol and bigger drops are called droplets)
One study analysed all the available research in order to compare how effectively can N95 (FFP2) masks and the normal surgical masks stop a virus sized like Covid (for this experiment, researches used Infuenca virus- not because those two offer similar sickness flow, but because they are similar in size and behaviour in aerosol). Based on the data of 6 studies involving 9171 patient, they concluded that the difference is of NO value to general population, meaning: for everyday activities, you should be equally protected, whether you wear a professional N95 mask or a normal medical (“surgical”) mask. Though that was all before covid19. Today we would perhaps want t0 revise this as general population is also facing larger risk.
OK, so how about the textile masks? Do they stop Corona Virus?
In a recent study researches evaluated 20 different textile masks on how well they can stop different particles. First they put those masks under the microscope in order to estimate the size of the pores. The smallest pore size they found in a textile mask was 51 micrometers (50x bigger than corona virus), and the biggest ones were 569 micrometers (approximately 500x bigger than the Covid19 virus).
The smallest pore size they found was 51 micrometers (50x bigger than corona virus), and the biggest ones were 569 micrometers (approximately 500x bigger than the Covid19 virus).
This pore size seems to be in correlation with the ability of the mask to stop the small particles. The authors also noted, that those pores also grow when mask is stretched.
Microscopic images of mask surfaces made of different materials
Yellow scale bar shown (yellow lime in the picture A) is 500 μm and applied to all images.
Source: DOI: 10.7717/peerj.7142/fig-2
As we commonly re-use our textile masks, researchers also washed them and put them under the filtering test again. This time the filtering efficiency was even worse then at the base line. To find the possible cause of change in filtering efficiency with washing and drying, the authors took a photo of the pores under the microscope after every cycle. Below the result:
Contrary to common belief, pores on a cotton masks enlarge after washing, amking the mask even less protective. Source: DOI: 10.7717/peerj.7142/fig-6
Another research rightly assumed that our multiple use masks are not all made of same textile. They assumed many people would turn to do-it-yourself solutions once the proper protective masks get sold or too expensive and respirators are left for medical professionals.
So the researchers took a few of house utensils and inspected their ability to help us.
This research showed that vacuum cleaner bags have the best filtering capacity, 94,35% just slightly lower than normal surgical masks(96,35%). Kitchen towel also showed surprising results, filtering 83,24% when placed in double layer. But, authors also conclude that:
1. An improvised face mask should only be used as the last alternative if the normal surgical masks and respirators are not available
2. The improvised masks could potentially help your surrounding not get infected by you.
3. However, textile and other improvised masks can provide wearers little protection from other infected persons.
4. Finally, any mask, no matter the filtration potential and fit, will have little to no effect unless used in conjunction with other protective measures, such as physical distancing, washing your hands and, should washing be unavailable, disinfecting them.
More important than any research: our habits or, how it all looks in reality?
For one reason or the other, many governments took up ordering the obligation of wearing (any kind of) face mask in all the publicly accessible areas. Additionally, the masks that, as we saw, actually provide protection against COVID (FFP2&FFP3) were in shortage, and it is appealed to public not to hord them but leave the available quantities for medical professionals.
Simultaneously, the price of surgical masks rose from 10 cent to anywhere from 1- 7e per piece in March 2020. Naturally, this left many families without the possibility to protect their own health using the mask. They were only focused on preventing getting fined. And so the use of the cotton masks started, although we saw that the protective effect they offer is extremely limited, even in the laboratory circumstances.
5 months later, in August 2020, another interesting experiment was published here. Admittedly, it is not the scientific article I usually go for, but I deemed their test legit and consider the findings very relevant.
For this experiment, random masks were taken from random people. Those were the masks they were about to (re)use. and the results were more than worrying: every re-used mask contained various bacteria and fungi, that can be very dangerous for the wearer!
These results are easy to explain: we put the mask on and off our face many times a day, many days in a row. In the meantime she is in the pocket, in the bag or any other place we quickly find for it. Until the next occasion when we grab it with the unwashed hands and put it back on the face. All the while, we know we will get fined if we don’t wear it, but were scarcely told how to actually place the mask and how to dispose of it.