By Mònica Ardanuy, Diana Cayuela, Enric Carrera and José Antonio Tornero from the Institute of Textile Research and Industrial Cooperation of Terrassa (INTEXTER)
Recently, some news items have appeared in which the efficacy of what are known as “fabric masks” is called into question. Before we look at the subject of efficacy, we should clarify that all masks are made of fibres (or threads) that form fabrics. Therefore, technically, all masks are made from fabric.
On first impression, some of them may seem to be made of plastic or paper. However, if we look at them with a magnifying glass we can easily see that they are comprised of fibres tangled together to form a fabric. If they did not have this structure, the masks would not be porous enough to allow us to breathe.
What are “fabric masks” really?
Masks can be classified in two different ways: according to the number of uses (one use or reusable) or depending on the final recommended use (personal protective equipment [PPE], surgical or non-surgical).
PPE and surgical masks are generally for one use only. Non-surgical masks are reusable up to a certain number of washes.
Hereafter, when we talk about reusable non-surgical masks we refer to those known as “fabric masks”. These masks are regulated by standards and should meet two basic technical requirements: filtration efficacy and breathability.
Masks that do not meet these standards are considered “homemade”. They do not meet any regulations and therefore we do not know how well they protect against the virus.
What is important is the level of protection
Classification of masks depending on the degree of protection can be related with filtration capacity. So, we can distinguish between:
- PPE-type masks: classified as FFP1, FFP2 and FFP3 depending on the level of filtration of particles in suspension (78%, 92% or 98% respectively).
- Surgical masks type I or II: with minimum levels of bacterial filtration efficacy of 95% and 98% respectively.
- Non-surgical masks: which could be of one us of various uses (reusable), with minimum levels of bacterial filtration of 95 and 90% respectively.
It is very important to clearly understand the meaning of the degrees of filtration and how they are measured.
PPE-type masks measure the capacity to filter particles of over 0.3 microns, while surgical and non-surgical masks determine the efficacy of bacterial filtration (particles larger than 3 microns). Therefore, the PPE-type masks have a high filtration capacity for particles that are 10 times smaller than the rest of the masks.
A high capacity of bacterial filtration of particles larger than 3 microns does not guarantee that a high percentage of smaller particles are filtered. A mask could be filtering a high percentage of bacteria but not viruses in suspension.
However, it should be considered that the virus is transmitted by air-borne particles (of a size smaller than 5 microns) as well as by droplets, which are much larger.
From all the above, we can obtain a first clear conclusion: PPE-type masks (FFP2 or FFP3) are what provide better protection against air-borne particles that contain virus.
These masks are particularly recommendable in small spaces that are not well-ventilated and have a high viral load. Health professionals who are exposed to these extreme conditions are the ideal type of user for these masks. This is the advice given by the Ministry of Industry, Trade and Tourism.
Do reusable non-medical masks protect us?
Firstly, no mask can guarantee 100% protection. As we have seen, even the most effective masks (PPE) have filtration levels below 100%. That is why it is very important to protect ourselves with other complementary measures such as distance and hand-washing.
However, just because a mask does not protect us 100% does not mean that it is not useful or that it does not protect us to a high per cent.
Depending on the context, one or another type of mask is recommendable. Healthy people should use non-medical masks, sick people should use surgical masks and people in contact with the virus should use PPE.
Does this recommendation make sense? In our opinion, yes. Depending on the situation we are in, there will be more or less concentration of virus particles and their propagation will be predominantly in the form or air-borne particles or droplets.
In some cases, it will be more important to protect others from the droplets that we emit when we speak, cough or sneeze than from potential air-borne particles.
In places where the probability of concentration of particles is very low (ventilated spaces, with an uninfected population that use masks and maintain the safe distance), protecting ourselves with a surgical or non-surgical mask could be enough.
In some cases, the levels of filtration of surgical masks and non-surgical reusable masks are similar. Therefore, reusable non-surgical masks can provide levels of safety similar to those of surgical masks.
Certified, well-used non-medical masks
If we choose a reusable non-medical mask to protect ourselves, we should ensure that it meets current regulations. Consumers should ensure that masks on sale meet the standards.
Just as it is vital to know a mask’s level of protection, it is also essential to ensure correct use. It is of no use to wear a high filtration capacity PPE mask if it is not well-adjusted to our face. It could be less effective in this case than a well-fitted non-medical mask.
In addition, proper cleaning and disinfection of masks is important. To achieve this, we should follow manufacturers’ recommendations or, if they are not provided, those of the Ministry of Health. In most cases, a normal washing machine cycle of between 60℃ and 90℃ will be sufficient.
So, if we choose a certified reusable non-medical mask and use it correctly, it will serve to prevent the release and propagation of the virus SARS-CoV-2. In addition, these masks are more comfortable and aesthetically pleasing than surgical masks or PPE. We will also contribute to the development and consolidation of the Spanish textile industry. By using them, we will help to stimulate our economy.
Using reusable non-surgical masks is more sustainable
Considering that a surgical mask weighs approximately three grammes, if each Spaniard uses three masks a week, we would generate 1,710 tonnes of waste a month.
The choice of reusable non-surgical masks therefore contributes significantly to reducing waste generation.
In addition, if their collection is managed correctly (including a previous disinfection system) they can be recycled and converted into new textile products.
Article published on 16 November on the website The Conversation