Man wearing mask in subway

Unmasking the facts

Four questions about the use of face mask — answered

Four questions about the use of face mask — answered


“Different types of masks provide different levels of protection against the virus and users should base their choice on the level of risk they could potentially face.”

Dr. Royth von Hahn
Senior Vice President, Medical and Health Services, TÜV SÜD Product Service Division

 Monday, April 6, 2020

The COVID-19 outbreak globally has led to an unprecedented increase in demand for masks globally.  Just like any other preventive measures, masks have the potential of flattening the curve as they can prevent infected people from spreading the virus and protect healthcare workers from infected patients.

While it is a common practice to wear a mask even when one is having light symptoms of a cold in Asia, this practice is less common in Europe and Americas. As COVID-19 is placing an increasingly high burden on the capabilities of health system worldwide, any other respiratory infections that could be avoided at a personal level would be considered a positive contribution to the fight against COVID-19. 

Although wearing a face mask does not completely prevent infection, it can limit the spread of the virus by blocking virus-laden droplets from entering the airways which is postulated as one of the main routes of transmission by the coronavirus. At the same time, user habits concerning face masks can have a profound impact on its effectiveness. Unless worn correctly, it may inadvertently increase one’s risk of infection.

The level of protection offered can also differ between varying types of masks. Dr. Royth von Hahn, Senior Vice President, Medical and Health Services from TÜV SÜD, notes, “There is a wide variety of masks available such as N95, KN95, FFP2, to name a few, and each serves different purposes. It is important to know their differences, the levels of protection each mask can provide and the correct use of various masks.

In this article, Dr. von Hahn provides further insights on four frequently asked questions around the correct use and efficacy of protective masks.


Different types of masks provide different levels of protection against the virus. Dr. von Hahn explains that users should base their choice on the level of risk they could potentially face.

  • Single use or surgical masks: In situations such as commuting to and from work, in privately arranged personal transport and visiting less crowded outdoor open spaces. Recommended if you want to avoid spreading any cold you may have. 
  • Surgical mask, self-inhalation filter type dust respirator or protective face mask: In high risk environments where there is a high chance of exposure or interaction with people who are unwell or are seeking treatment
Mask by risk level 

The World Health Organization (WHO)[1] states the use of mask is part of a comprehensive strategy of measure to suppress transmission and protect yourself and others. It is advised that individuals wear a fabric mask unless in a particular risk group. For individuals above 60, have underlying medical conditions, feel unwell and/or looking after an ill family member, a medical / surgical mask is strongly encouraged. However, the situation is dynamic and changing constantly; do check official sources frequently for the updated information. Choose to buy only what you need. 


Protective masks can differ in terms of their Bacterial Filter Efficiency (BFE) and Particle Filter Efficiency (PFE) properties. BFE measures the filtration efficiency of masks using mean particle size (MPS) in bacterial challenge at around 3.0 microns; PFE, on the other hand, measures the filtration efficiency of a mask using non-living, nonviable particles fixed in size from 0.1 microns. Masks with PFE properties will provide users with better levels of protection as the coronavirus itself measures between 0.05 and 0.2 microns in diameter. The two most widely available types of masks are:

  • Cloth and paper masks: These are also commonly referred to as one- or two-ply masks and are effective in preventing large particles expelled by the user from reaching the environment. It has also been found and tested to be non-fluid resistant . This affects its protective qualities, making it less effective in protecting wearers against the virus. For this reason, its use should be restricted to low-risk situations.
  • N95 respirator: This mask does reduce the user’s exposure to very small airborne particles or contaminants but may not protect against sprays and direct liquid splashes. The N95 respirator mask is different from the N95 surgical option which are used mostly in the medical field. 

Unlike the abovementioned varieties, surgical masks and medical-grade N95 masks offer the same bacterial filtration efficiency (BFE) of no less than 95%. Users should note that wearing a disposable medical mask provides enough protection if they are in a public place without contact with patients.


What is in a surgical mask



Surgical masks will need to conform to international medical health product standards. Manufacturers are responsible to ensure that the masks are tested or approved to the relevant product standards as required in the country where it is sold. The standards vary from country to country. There are various local standards that apply in testing the efficacy of masks such as BS EN, ASTM and GB. Some of the standard tests for protective masks include particle filtration efficiency, bacterial filtration efficiency and antibacterial efficiency tests. "Other testing parameters include breathability, flammability, resistance to liquid penetration and fit," notes Dr. von Hahn.


Be sure to check the use-by date on your mask. Masks that are past their expiry dates may not be able to provide the same level of protection and may be subject to degradation. Always purchase your masks from known sellers and websites to ensure their authenticity and quality.

When purchasing masks, always check the packaging details to ensure the effectiveness and quality of the masks. The packaging information typically includes: the name of the manufacturer and the relevant model number, an indication that the particle filtration efficiency is 80% or higher for surgical masks and more than 95% for N95 respirators and expiry dates.

Many companies globally are doing their part in pandemic relief by converting their production facilities to produce face masks or other critical essential medical supplies. TÜV SÜD is also contributing by working with our customers to expedite the testing process to ensure the essential medical supplies exported meet the target market’s requirements.

The European Commission has released a document on Conformity Assessment Procedures for Protective Equipment for prospective manufacturers who would like to support the pandemic relief.


‘Extended use’ refers to the practice of wearing the same respirator for repeated close contact encounters with suspected cases of infection without removing the mask in between. Reusing the same mask usually means the usage of the same respirator during multiple encounters with people or re-using a respirator on different occasions. While individual preferences may differ, it is strongly recommended that users should never share the use of the same mask and should not reuse single-use masks. (Source)

Do not use disinfectants, alcohol or apply heat to disinfect the mask. If it is dirty, damp or deformed, the mask should be replaced.


Wearing a mask is just one of the preventive measures necessary to combat the pandemic. There are other important practices which we should adhere to:

  • Practice good hygiene: As the virus continues its course, the best way to fight it is to practice good hygiene, wash your hands frequently with soap and water, see a doctor when you are unwell and avoid crowded places. Users should always pair the use of masks with basic hygiene habits like washing of hands regularly and avoiding public gatherings. Being aware and applying these usage steps and habits will go towards safeguarding not just one’s health but also reducing the risk of infection and nipping the spread of the disease in the bud. 
  • Social distancing: Keeping a distance of at least 1 meter away from someone who is sneezing or coughing will reduce the chance of becoming unwell and weakening the immune system.

[1] This paragraph has been updated on 3 November 2020 based on the latest WHO guidelines. 


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