Unfortunately, the coronavirus pandemic has also brought some myths about respiratory protective equipment which has spread together with the pandemic. These myths concern especially the FFP3 respirators and their fitness to be used for medical purposes. Where do these respirators really stand concerning their efficiency and safety compared to nanofiber facemasks?
The bottom line of the problem with common respirators is that their efficiency relies on electrostatic filtration. The electrostatic charge of a filter discharges very quickly after coming into contact with liquids or air humidity and that leads to a substantial decrease of its efficiency. If a user wants to stay protected, he or she must take the respirator off his or her face after approximately 30 minutes – once the filter dries out, its level of efficiency will increase again. Some producers solve this problem by adding a layer of activated carbon which absorbs humidity and extends the life and efficiency of the filter . Nevertheless, the producers often give different reasons for the use of activated carbon in their effort not to devalue their goods in the eyes of their customers.
Electrostatic versus mechanical filtration
Compared to that, the efficiency of nanofiber filters is based on mechanical principle which is why they work so well even after they come into contact with humidity. Also, it is reasonable to point out that human breath itself is humid. This means that the using of a respirator by a person – in other words, putting it on and breathing through it – already lowers the level of protection that the respirator may offer. But nanofibers, thanks to the density of the material that they are made from, still maintain top-level filtration. The filtration efficiency of nanofiber respirators even increases at the time a person is wearing one because the filter gets denser thanks to intercepted particles – but not to the extent which would reduce the breathability of the filter.
If you want to protect yourself against viruses by a standard respirator with a polypropylene electrostatic melt-blown filter, a certified FFP3 respirator (according to the EU standard EN 149) is the only option. As the only product in this category it can very likely ensure the filtration of viruses. However, it is necessary to point out that respirators are designed primarily as protective equipment for workers and professionals, which means they are tested especially on their filtration efficiency of solid or liquid particles, not microorganisms. Their ability to intercept viruses was not taken into consideration when decisions on the design of respirators were made and the EU standards do not even require such functionality.
The information that FFP3 respirators provide protection against viruses is more of “a wish” based on the following assumption: If a product intercepts paraffine oil (one of the tested substances), it will also intercept viruses. All in all, it really can be partially inferred that if a respirator intercepts oil it will also intercept microorganisms. Because they travel through the air in droplets that come from coughing, speaking and breathing – in practice, thanks to the density of their melt-blown layers, most of FFP3 respirators do intercept viruses. But it is possible only at the expense of their breathability because the filter needs to be extremely thick and dense.
Usually, FFP2 and 3 respirators have what is called an exhale valve, so that a person can breathe through them during his or her day-to-day activities. But the valve becomes a weak spot when used for protection against viruses and bacteria because in a few dozen of minutes or a couple of hours pathogens can get in through it. The valve is not there to filtrate, but to reduce air humidity – it keeps the respirator dry and helps to extend the efficiency of its electrostatic filtration. At the same time, it improves the comfort of its user – the higher the class of the product, the more reduced the breathability of the product without a valve. So, the valve helps to rid the respirator of warm air on the inside (it is not a coincidence that it is used especially for operation at places with hot and humid conditions, like glass factories or steel mills).
For protection against tiny solid particles (dust, smog, pollen) which should stay out of a person’s airways, a FFP3 respirator with an exhale valve serves well. However, as protective equipment for professional purposes these products are not designed to protect the user’s environment from him or herself. At first sight, one can see this as an insignificant detail, but when their current use for protection against the coronavirus is taken into account, it becomes a serious issue.
It is not a coincidence that the relevant standards define protective equipment for medical purposes (a face mask) as a tool primarily intended for the protection of others from its user. Therefore, so as not to spread their own droplets among patients, it is face masks that are used by doctors and hospital staff most frequently. By doing this, they try to prevent cases where a medic is sick but he or she doesn’t know about it yet – they show no symptoms, but the person can become contagious and put people with, at most times, a weakened immune system at risk.
How to protect medical staff and patients
To summarize the above: an FFP3 respirator, which usually must have an exhale valve, is not appropriate protective equipment for medical purposes. It can provide a doctor with some protection, but that doesn’t apply to people around him. A potentially infected member of frontline medical staff can spread an infection through the exhale valve – unknowingly, yet uncontrollably and in a much higher concentration.
Let’s apply these findings to the current situation: a doctor has no idea that he or she has been infected (whatever the cause might be) and examines people with a suspected coronavirus infection. If their tests results are negative, coming to hospital put them at unnecessary risk of possible infection from a doctor “protected” by a respirator. This unnecessary risk mostly concerns people with a weakened immune system like seniors, oncology patients after a chemotherapy, individuals that suffer from cystic fibrosis, people with chronic asthma etc. Therefore, we argue that medical staff need to stop using respirators with exhale valves and supplying hospitals with these respirators is a proof of lack of knowledge of this issue.
Nevertheless, even respirators without the exhale valve have a lot of disadvantages: usually their breathability is not sufficient (it is difficult to breathe through them), they are not comfortable (because of their weight, rigidity and stiffness), because of their proportions they are not easy to store and also, they do not rank among the cheapest choices. Contrary to that, nanofiber protective equipment can intercept tiny particles mechanically – on the principle of a miniature sieve which intercepts also particles which are only a few micrometers in size. They are cheaper than FFP3 respirators and maintain their efficiency level regardless of humidity. Thanks to the extreme density of nanofibers, a nanofiber filter can be much thinner than melt-blown filters, therefore a person can breathe much more easily through nanofiber face masks. Therefore, they don’t need the unsafe exhale valve, which guarantees a higher level of safety and reliability.
People often ask why nanofiber masks don’t have the FFP3 certification class when they filter particles and microorganisms with higher efficiency than respirators for professional purposes. The reason is simple – because of the aforementioned thinness of nanofiber filters, paraffin oil used in testing can get through. While in protective equipment for professional purposes this would be an imperfection, for protection against viruses it doesn’t matter. Therefore, in this case the FFP2 category is sufficient for nanofiber products, accompanied by individual testing on filtration efficiency of viruses and bacteria – in our case carried out in an American institute Nelson Labs. The dispute between the efficiency of nanofibers and the officially inferior protection FFP class results also from the obsolescence of the standards. They were created several years ago when people didn’t work with nanofibers yet, and therefore they don’t take into consideration new materials and technologies which combine efficiency with comfort much better.
Let’s conclude that training programs for medical staff, which train them to use protective equipment, are sometimes outdated as well. They often result from dogmas that were surpassed a long time ago, but which have not yet been surpassed in health care. Therefore, not by their own fault, doctors often lack elementary knowledge about how to use face masks and other equipment correctly. To improve the situation, we instruct all distributors of RESPILON products to advice hospital staff on their own protection as well as the protection of their patients. We also educate our end customers in retail about regular protection, as well as about protection in times of epidemics and pandemics.