A quick guide to choosing the right mask for you to offer maximum protection against COVID 19 air-borne transmission

 

 

Starting at the beginning, most transmission of the COVID 19 virus between humans occurs by air-borne particle transmission. This is most common when we sneeze or cough – expelling these droplets with great force and considerable distance. The best way to stop this transmission is by social distancing and the wearing of some form of face covering.

 

 

Face coverings come in a myriad of different designs and descriptions. Here is a summary of a just few of the currently available options – fabric face covering, surgical mask, FFP 1,2 and 3, Type IIR, N95 and so on – the list is extensive!

 

But which is the best mask to wear to offer maximum protection against air borne COVID 19 virus particles?

 

 

Starting with the least protection, these are fabric face coverings. Often home-made at the start of the pandemic these are now even a fashion accessory produced by well-known designer labels to promote their brands on your face! The main problem with a fabric face covering is there is no certainty of how effective it is in preventing air-borne droplets passing through the material. This is due to the variability of materials available and the thickness / density etc. Unfortunately, a thicker and denser material may offer better filtering efficiency but, in most cases, it will also offer greater breathing resistance which makes wearing these face coverings uncomfortable and sometimes difficult to breathe through. Then there is the issue of re-usability. Are the masks contaminated after wearing and if so how does washing them effect this? Studies have shown that washing fabric masks at less than 60 degrees will not remove the COVID 19 virus completely. Therefore, this is a major issue with such masks.

 

Surgical masks on the other hand are designed and manufactured to specifically cover the wearer’s mouth and nose. However, these often have ear loops rather than head straps and are loose fitting – especially at the sides of the face, thus allowing air-borne droplets to enter behind the mask and pass into the lungs. These masks are predominantly designed to protect others rather than the wearer from contamination.

 

 

And what about Type IIR masks? These are defined as medical face masks made up of multi-ply construction that prevents large particles from reaching the patient or working surfaces. They include a splash resistant layer to protect against blood and other bodily fluids, often of a pleated design. Type IIR face masks are tested in the direction of exhalation (inside to outside) and mostly have ear loops to hold the mask on the wearer’s face. They are generally not tight fitting to the face across all the mask extremities.

Therefore, the only method of effective self-protection is for the wearer to don a recognised and laboratory tested and accredited FFP (filtering face piece). These come in various categories – FFP1, 2 and 3. These masks are tested and accredited to an International Standard: EN 149:2001 +A1:2009.

But what are the differences in the FFP categories? Basically, it is the particle filtering efficiency that varies between the different classes of mask. FFP1 classification masks offer less filtering efficiency (80%) that FFP3 models which have a greater than 99% capacity.

In general, the choice of mask classification should reflect the risk in the environment it is being worn. For this reason, healthcare staff in hospitals generally wear FFP3 masks to ensure maximum protection. To ensure you have this same level of maximum protection it is advisable to always choose an FFP3 model from a reputable Manufacturer. To ensure this is the case look out for a CE Mark and a four digit Notified Body number by this – actually printed on the mask. The Notified Body is responsible for testing the mask against a set of criteria to ensure the performance matches the claims by the Manufacturer. If it doesn’t then the CE mark will not be awarded for that product.

 

Different countries offer different classifications of mask efficiency. For example, in America the classification is “N95” or 95% filtering efficiency, and in China the same is classed as “KN95”.

FFP model masks also have a guaranteed maximum inward leakage rate. For FFP3 masks this is less than a 2% limit. There are also strict limits on such design factors as breathing resistance and shelf life. The maximum usage lifespan of a mask is also defined, with many modes stating “NR” on the mask material. This means “non-reusable”, indicating the mask must only be worn once. Many masks use electrostatically charged fibres to effectively capture and retain the very small contaminated particles which try and penetrate the layers of fabric. The science behind Brownian Motion (which is often studied at school) helps explain this phenonium and explains why they have a “use by” date to ensure this electrostatic charge is retained and not dissipated over long timeframes.

Finally, to really ensure a proper fit and maximum protection always ensure you have a Fit Test for the FFP mask you choose to ensure this is the right mask for your face shape and dimensions. Always use an accredited Fit Tester to conduct your assessment.