Medical Face Masks: Should I use them?

Medical Face Masks: Should I use them?

Medical face masks and Coronavirus, will they protect me? Let’s discuss the veracity of such an important issue as well as its different types.

Current situation

Right now, the SARS-CoV-2 has caused more than 16 362 deaths. With an infection curve that is dangerously increasing as the disease spreads.

Infection curve

Figure I. World infection curve since January 22.

But the number of people who want to take care of their health is also increasing

Control measures

One of the measures to prevent the spread of COVID-19 is using PPE (personal protective equipment).

From this group, face masks are the ones that are what are causing more concern.

I do not know if this is due to the perception of their efficacy, price or accessibility. Perhaps it is simply because it is a common accessory in healthcare and people have seen it in movies and TV shows.

TV Shows depiction

Figure II. Image from the TV show House MD where we can see a medical mask. 

The truth is that currently medical face masks have become a very valuable item. In fact, there is a general lack of supply since distributors are not capable of meeting the demands due to the pandemic.

What are medical masks or face masks

Face masks are a personal protective equipment that cover the airways, preventing the pathogens from entering our body. They are also known as respiratory protection devices or RPDs.

Are all of them the same?

No, they are not

There are difference between masks and respirators. Although people do not know the different between them.

Medical masks

The classic face mask of a doctor like the one from the previous picture is a medical mask. But they have to labelled depending on their use: dental, isolating, surgical…

It is part of the personal protective equipment of a healthcare professional in order to avoid being exposed to a pathogen that can be transmitted through the droplets from the mouth and nose from others.

It can also be used in order to avoid spreading the disease to others with your own oronasopharyngeal fluids.


Figure III. Image from the TV show House MD

This is the main reason why we use this type of protective system. In fact, healthcare professionals use it during surgeries in order to prevent infections and sepsis that could come from the surgeons.


On the contrary, respirators are protective devices that are used to protect the wearer from air pollution.

These accessories provide more protection against pathogens which can cause infections through aerosols. They are classified depending on their ability to filter specific particles in standardized tests:

The popular N95 means that it filters a 95% of said particles.

  • If the respirator is labelled with an R, it means that it is resistant to small oil droplets (1-10mcm);
  • If it is labelled with a P, it means that it is extremely resistant.

That is, these devices are ready to face infectious bio-aerosols and contaminants with a small particle size.


Figure IV. Worker wearing a respirator.

Then, it would seem logical that respirators are better than medical masks when it comes to preventing an infection, right? Well, now you will see that it is not as simple as that.

Can face masks help to prevent infections?

Yes, at least it seems that there is a positive trend.

In other words, face masks are a real and effective physical barrier against specific pathogens.

The problem is that there is a severe lack of accuracy in the trials that have been conducted.

Limitations of the studies

Many of them are observational, they do not perform serological tests and they determine the result according to the symptomatology.

Others do not have a control group, they do not take into account the transmission features of the pathogen, or the type of exposure from the sample…

Therefore, we have to control the factors that cause bias in the results of the studies.


Still, we can have a look at the meta-analyses like the ones by Jefferson et al., (2009). He concluded that wearing a face mask lowers the risk of infection, which was even more effective than other strategies like washing our hands frequently.

Effects of handwashing

Figure V. Tree diagram about the effects of washing our hands frequently and using face masks among healthcare professionals. The result was that those who use these strategies have lower chances of being infected.

The truth is that “wearing a face mask” is a very wide concept: it does not include other protective services, the time or the way we have to use it in specific situations.

Face masks

Therefore, “wearing a face mask” lowers the risk of suffering an acute respiratory syndrome.

Differences between exposures to pathogens

Not all viruses are the same.

When we talk about a virus like influenza (the flu), the results are quite controversial.

There does not seem to be a homogeneous reduction of the amount of infections caused by the virus. In fact, the positive tendency is associated with the use of face masks and other PPE and its early, consistent and proper use. (bin-Reza et al., 2012).

However, the SARS (severe acute respiratory syndrome) was reduced in 8 of the 9 reviewed articles, even if the frequency of the infection with influenza is not homogeneous.

Contrasted Effectiveness

Still, official face masks and respirators are effective for healthcare professionals and workers who are exposed to pollution.

At least, as part of a series of strategies (gloves, frequent hand disinfection, special suits…) in order to reduce the infections caused by SARS.

I have made a super-effective homemade face mask

During the last weeks and due to the lack of medical protective equipment we have witnessed how some people have come up with their own respiratory protective devices.

Homemade face masks

Figure VI. Homemade protective masks.

Even though this inventions are an ode to the imagination, they are completely useless.

In fact, we are even questioning the efficacy of face masks and respirators made with tested materials to filter micro-particles.

How is a homemade mask going to be able to prevent an infection?

It is much more effective to distance ourselves from others, at least 1.5m, than building a barrier that does not really work.

Cloth face masks

Many of you have probably thought that:

“…I can wear a scarf or something similar to cover my mouth and nose…”

The truth is that apart from not protecting, since the material has a porosity that is superior to the diameter of any virus, it can also be harmful.

Attack rate %

Figure VII. % of onset of clinical respiratory disease (CRI), influenza-like illness (ILI) and some viruses (Virus) in subjects who wore homemade cloth masks, control group and subjects with medical masks.

Using cloth masks increased the risk of infections and the onset of respiratory disease in a sample of 1607 healthcare workers from Vietnam.

This is possibly due to the false feeling of safety they produce, which made people get closer to each other, taking less precautions. Not to mention how many times people touched these devices to adjust them to the face, increasing the risk of infection drastically.

In this study, the use of face masks reduced the ineffectiveness rate of the virus (confirmed by serology), in a 0.7% when compared to the control group. In other words, from 1000 exposures, 7 infections less, not so bad.


  • Social distancing
  • Wash your hands properly
  • If you have a face mask, use it
But do not make one yourself unless your are doing that as a hobby or to hang it in the wall once this is all over.

What is better, a respirator or a medical mask?

Even though the answer may seem simple… It actually is not.

Smith et al. (2016) compared the studies that assessed the effects of medical masks and respirators (N95) about the infection degree of the sample.

The authors concluded that there are no significant differences about using medical masks and respirators.

In fact, they believe that even though respirators can be superior in laboratories and similar conditions, this is not so clear in the clinical environment, specially due to the discomfort of respirators.

Manipulation of respirators

These devices seal the face area that they cover while masks do not. Even doctors forget and they do not manipulate these devices properly, adjusting them with their hands and changing their position:

Thus, the face is exposed to a new contamination, eliminating any possible benefit (Smith et al., 2016).

Effects of using a respirator

Figure IX. Effects of using a N95 respirator vs a medical mask and the risk of infection in laboratory, RCTs, cohort studies and controlled-case studies. The left area indicates the superiority of respirators, while the right supports the use of a medical mask.

Who should use them

The WHO recommends using respirators for healthcare professionals exposed to infected patients with viruses like the MERS-CoV or Ebola. They should have a filter equal or higher than 95% of the particles of 0.3 micron diameter (N95).

This is due to the fact that not all studies show the same results. For example, in this case, the general use of N95 was superior to its punctual use (obviously). But the general use of medical masks also reduced the number of infections through droplets (both from bacteria and viruses, including influenza (flu)).

Relative risk of infection

Figure X. RR of infection with bacteria, virus, flu and any other pathogen that can be transmitted through droplets after a general and punctual use of a respirator N95 and a face mask compared to not using these devices. Towards the left indicates the benefits of using them.

The authors point out the need of emphasizing the importance of healthcare workers using respirators with a good filter when they are exposed to the pathogens.

Apart from instructing how to use and manipulate them.

More controversies

However, once again, Radonovich et al. (2019) published a RCT in JAMA about the good methodological quality of 2862 healthcare workers that shows that there were no significant differences between using a respirator N95 and a medical mask on the onset of infections with influenza. A 1% less in face mask users.

Still, let’s not forget that influenza is not like SARS-CoV-2, which is why the results are not completely extrapolated.

Risk of infection influenza

Figure XI. Tree diagrams that determines the RR of infection with influenza in laboratory (A) and others depending on the use of respirator (positive towards the left) or a medical mask (positive towards the right).

Should I use a mask?

In principle, no, but let me explain.

It does not mean that it is not effective. On the contrary, it means that you are not going to be as exposed as a doctor or any other healthcare professional.

You may have noticed that people are insisting that we should not use face masks against COVID-19.

This is due to the fact that there is a terrible lack of resources and our professionals are working with disposable masks for days. Consequently, this increases the risk of infection for them, even if these devices still do their function.

Healthcare professional are the ones trying to save our lives. They are being exposed to the pathogen because you are scared of going out to buy bread in case someone gets close to you.

By no means I am not saying that you should not be afraid, but you should be responsible, stay up to date and be cautious when you go out.

But believe when I say that it is easier for you to maintain a distance of one meter and a half, than a doctor who is treating patients and being exposed to bio-aerosols just to diagnose them.

In fact, there are many healthcare workers who have been infected due to a lack of self-protection measures. This is partly our fault since we were told not to buy this equipment.

Official Statements

A professional that is exposed should use FFP3/N95 face masks when diagnosing patients. But they do not have the necessary tools, so they are running an unnecessary risk.

Government statement

Figure XII. Infographics published by the Spanish Health Ministry in the last edition about the protection against occupational risks due to the COVID-19.

We need more empathy and limit the use of face masks for sick people or those who are healthy but who are treating those who are sick. As well as those who spend long periods of time in “contaminated” areas, such as a shared apartment, a car or similar.

Advice from the CDC

Figure XIII. Advice from the CDC.


  1. bin-Reza, F., Lopez Chavarrias, V., Nicoll, A., & Chamberland, M. E. (2012). The use of masks and respirators to prevent transmission of influenza: A systematic review of the scientific evidence. Influenza and Other Respiratory Viruses, 6(4), 257–267.
  2. Brown, C. K. (2019). Respiratory Protection Against Emerging Infectious Diseases: Face Masks, Respirators, and Tools for Choosing between Them. Health Security, 17(2), 133–139.
  3. Cascella M, Rajnik M, Cuomo A, et al. Features, Evaluation and Treatment Coronavirus (COVID-19) [Updated 2020 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.
  4. Centers for Disease Control and Prevention. (2020, 20 marzo). Coronavirus Disease 2019 (COVID-19) – Prevention & Treatment. Recuperado 25 marzo, 2020.

Study 6-11

  1. Jefferson, T., Del Mar, C., Dooley, L., Ferroni, E., Al-Ansary, L. A., Bawazeer, G. A., … Rivetti, A. (2009). Physical interventions to interrupt or reduce the spread of respiratory viruses: Systematic review. BMJ (Online), 339(7724), 792.
  2. MacIntyre, C. R., Chughtai, A. A., Rahman, B., Peng, Y., Zhang, Y., Seale, H., … Wang, Q. (2017). The efficacy of medical masks and respirators against respiratory infection in healthcare workers. Influenza and Other Respiratory Viruses, 11(6), 511–517.
  3. MacIntyre, C. R., Seale, H., Dung, T. C., Hien, N. T., Nga, P. T., Chughtai, A. A., … Wang, Q. (2015). A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open, 5(4), e006577.
  4. McCoy, C. E. (2017). Understanding the intention-to-treat principle in randomized controlled trials. Western Journal of Emergency Medicine, 18(6), 1075–1078.
  5. Radonovich, L. J., Simberkoff, M. S., Bessesen, M. T., Brown, A. C., Cummings, D. A. T., Gaydos, C. A., … Perl, T. M. (2019). N95 respirators vs medical masks for preventing influenza among health care personnel: A randomized clinical trial. JAMA – Journal of the American Medical Association, 322(9), 824–833.
  6. Smith, J. D., MacDougall, C. C., Johnstone, J., Copes, R. A., Schwartz, B., & Garber, G. E. (2016). Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: A systematic review and meta-analysis. Cmaj, 188(8), 567–574.

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About Alfredo Valdés
Alfredo Valdés
A specialist in Pathophysiology and biomolecular effects on nutrition and sportive activity who will show you the elaborate world of sports nutrition in his articles, employing a simple and critical writing.
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