True or false? Washing hands is useless because people don’t do it right and because they touch their face too often!FALSE! But why do we hear the same arguments about wearing hygiene mask (surgical masks) to prevent the spread of the respiratory disease COVID-19? Shouldn’t we rather teach people how to wear masks properly, and how to keep the hands clean?

Hygiene masks against COVID-19 have become the subject of heated discussions in Europe, especially now that Austria has taken the step to make them mandatory for grocery shopping. For some, wearing masks is just „useless“, while others see them as the ultimate solution. The truth is, as often, somewhere in-between. 

My position is that it depends on the situation and the type of mask. Respirator filter masks are essential in high risk situations. In all other situations where either many people pass by in short time, or where some people are in proximity to each other for an extended time, hygiene masks can be an important addition to measures such as social distancing and washing hands.

Finally, if the call to not wear masks is because there are not enough of them, then authorities need to be honest, introduce a rationing system, kick-off industry production and test and explain how self-made masks can be made to be „better than nothing“ (actually if done correctly they can be about as good as commercial hygiene masks).

Type of mask – when to use what and why

The scientific fundamentals about the efficiency of different types of filtering masks and materials date back several decades. Researchers looked at the effectiveness of filter materials and compared mask types using either testing particles such as salt crystals but also aerosolized bacteria . More recent research (mine included) focused more on usability and user compliance, and alternative filtering materials including whether using nanofibres are safe for use. Some research also investigated the use of masks for epidemics such as influenza or SARS.

High Efficiency Respirators (FFP2 and FFP3) with face shield are warranted for personal protection in high risk situations such as medical staff directly interacting with patients. This can be further heightened to a positive pressure hood with filtered air supply for staff spending an extended time in atmospheres where mechanical forces can lead to fine aerosol in the air.

Surgical or hygiene masks, in contrast, should be seen as an emission control device that provide also some protection for the wearer, as seen in healthcare workers for influenza*. Critics say that there is very little evidence that hygiene masks prevent the spread of diseases. But “the absence of evidence is not evidence of absence“ (quote from a nice commentary in Lancet). The truth is that there are simply not enough studies to unterstand how well it works for the general population. Therefore, we have to deduce from what we understand about respiratory diseases and from studies done in worker populations and in lab settings.

Respiratory emissions of viruses will occur usually associated with droplets, most of them will be large but some can be very small. This was investigated in a nice laboratory simulation: Especially in rooms with poor ventilation, wearing masks strongly reduces the inhaled aerosol exposure of others. Respiratory emissions also pose a problem as a source of surface contamination. Thus, hygiene masks will reduce both, contamination of surfaces and concentrations of airborne particles, if used correctly

Self-made masks, finally, are better than nothing to prevent the release and do provide some respiratory protection against the larger droplets that can carry many more viruses. If crafted correctly they can actually perform as well as good hygiene masks.

*) When used against large aerosols and bacteria, good quality hygiene masks have about 95 to 97% efficiency, if worn correctly. Be aware that not all hygiene masks perform well, and most hygiene masks’ performance will drop dramatically when you get into the size range of individual viruses and diesel particles. Actually, also some N95 respirator face masks were not a very good protection against individual viruses, though they perform in general much better than hygiene masks.

What can be done if there are no masks?

The internet is full of guidance on how to tailor your own mask. Be aware that many of these procedures are not quality tested! I hope that governmental task forces and institutions competent in textile technology (e.g. Swiss EMPA) and biosafety (e.g. biosafety labs Spiez) can develop and publish guides for making masks at home that perform reasonably well. Until such guidance is available, here a few tips for increasing the safety of your self-made mask:

  • Get a pattern for a mask that fits the shape and the size of your face. It must cover your nose.
  • The mask must also fit well at the edges.
  • The mask must remain comfortable when worn for many hours, so pay attention to the ear-loops or head bands.
  • Use several layers of materials that have low air resistance, to make breathing easy and to avoid side-stream leakage.
  • Consider soft edges at your mask. For example, polypropylene filter napkins as filter and side edge material were found to result in quite effective masks.

Remember that your self-made mask is not a good protection, just „better than nothing“ if worn correctly. The main purpose is to protect others from your droplets. Please replace and wash masks after each use and check their integrity after each washing.

Tips for safely using masks

These tips are intended as a quick guide. Please check carefully what is known for your type of mask, what the producer recommends and what your employer asks you to do. If in doubt, contact a safety and health specialist!

Masks as a source of infection

It is not enough to wear a mask. A mask can become a source of infection for ourselves if we don’t follow proper hygiene rules. A mask has two sides: an inner side, which is collecting our respiratory droplets, and an outer side, which becomes loaded with whatever is in the air surrounding us. What does that mean?

  • The outside can infect you if you have been near people that have the virus (and you can’t tell if they do). This is why you have to wash your hands after touching the outside.
  • The inside can infect others if you are (unknowingly) infectious. This is why you have to wash your hands after touching the inside.

This is also why you should not touch your mask, after you put it on.

How to put on a mask

How to put on your mask depends on the mask type. There are excellent visual guides on the pages of NIOSH and also on wikihow. But there is also a procedure around these steps:

  • Put on the mask in a clean and well-ventilated place, thus before you get into the mask wearing zone so you want to have it already on your face when you need it.
  • Wash your hands and – if possible – also your face
  • Put on the mask as shown on the visual guide (respirators / hygiene masks): Thus, check it is intact, place it from the front, make sure you cover your nose. Adjust the mask to fit your face.
  • Make sure that there are no openings on the side of the mask. They will let air pass unfiltered. Especially the areas around the nose and under the chin are critical.
  • Wash your hands once you are done.
  • Don’t touch your face. Don’t touch your mask.

How to adjust or lift the mask

There are situations where the mask has moved or is just not comfortable. While it is best to not manipulate the mask, it may still be necessary to adjust or even lift it.

When you need to adjust the mask, e.g. because it is no longer in the correct position, follow these steps:

  • Look for a place without people nearby, to prevent accidental contamination
  • Wash your hands
  • Do not lift off the mask unless you are in a well-ventilated clean place
  • Adjust the mask but avoid touching the filter material
  • Wash your hands

You also may be thirsty and want to take a sip, or have another reason to want to access your mouth or nose.

  • Look for a well ventilated clean place without other people nearby
  • Remember, inside is your stuff, outside is polluted from your surrounding
  • Wash your hands before touching the mask
  • Lift the mask with one hand and hold it in position
  • Do what you need to do (drink your drink /take out the chewing gum/ clean the nose …)
  • Put back the mask and make sure it is still a good fit
  • Wash your hands

How to take off the mask

Masks should be taken off only once you are in a clean well ventilated zone without other people nearby (not even those you are living with to avoid contaminating them during this procedure)

  • Wash your hands
  • Hold the mask at the bands or ear-loops only
  • Dispose of the mask if it is a disposable one / OR store it in a plastic bag or container until it can be washed
  • Do NOT wear a mask a second time unless it can be washed (and was washed)
  • Wash your hands to finish off

Attention: washable masks remain contaminated until they are washed. So when you wash them, open first the wash drum so that you can directly place them into washing machine after you opened the bag or container. Wash them as hot as possible for the fabric but at least at 50°C. Remember that also the container needs to be washed or the plastic bag dumped.

How often to change a mask

Masks have to be disposed or cleaned on a regular basis. How often depends on the situation:

In professional settings, disposable respirator filter masks are usually dumped each time you take them off after having been in proximity to a patient. However, in a time of shortage, reusing by disinfection seems possible in some situations and for some filter types. Check with your company’s health and safety expert before doing this!

Hygiene and surgical mask should be dumped after each use but at the latest when they get soaked from the inside. This is because the wetted tissue will block the air flow through the filtering material, causing a strong increase of leakage air from the mask’s side. In any case do not wear a mask more than one day.

Home-made filter mask have to be dumped or washed after each use or when the inner layer gets soaked. It is best if you change them every few hours and put the used washable ones in an air-tight plastic bag or container until you can wash it (see above for washing tips).


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