[Ask Dr Chiu] Demystifying masks

[Ask Dr Chiu] Demystifying masks

[Ask Dr Chiu] Demystifying masks



5  Mins Read

Six months back, if someone told you that people would queue up on the street throughout the night in cold weather just to buy a box of face mask, you would think that this must be a joke. Now, this phenomenon has become an everyday affair. While you are scrambling to buy face masks, do you know that different types of masks serve different purposes? Which is the most suitable type of mask to protect us from the novel coronavirus?

Here are the three most common types of masks:

1. Surgical mask

The surgical mask is most suitable for community use. It has three layers: the outer layer (colored side) is the liquid repellent layer, the middle layer is the filter and the inner layer (white side) is the moisture absorbent layer. The colored side of the mask should ALWAYS be outward facing. Rumour has it that healthy people should wear the mask inside out – this is wrong! Having the white side facing outwards will increase the chance of viral droplets being trapped onto the mask surface. The wired side should always be on the top and mould to fit the shape of the nose. The mask must also cover from nose to chin for proper protection. Different countries have different standards regarding the specification of masks, and it is very difficult for non professional to judge which is appropriate. In short, if it is a surgical mask, if it has three layers, and if it is bought from a reputable source, then it should be adequate.

2. Pollen mask

The pollen mask is not suitable to protect against the virus as a large portion of its material is not liquid repellent, which may attract droplets to be adhered to it and raise the chance of infection. Moreover, it can only filter large particles but not droplets, so it is only suitable to filter out pollen during the pollen seasons.

3. N95 mask

N95 mask is actually not recommended for daily use due to the following reasons:

  1. N95 mask require one to undergo a fitting test to decide which model to wear. Wearing a wrong model of the mask runs the risk of breathing in unfiltered air.
  2. N95 mask causes re-breathing. Prolong wearing of such sealed masks will cause headache and nausea due to the rebreathing of the exhaled carbon dioxide.
  3. N95 mask is a tight fitting design and can cause skin irritation and even skin ulcer after prolonged use.
  4. Because of point 2 and 3, people tend to touch and adjust their N95 masks more often. This in turn will increase the risk of contacting the dirt and droplets trapped on the surface of the mask.

So if I really can’t get hold of a new surgical mask, are the following ways recommended?

1. Steaming used masks

No. There are videos being circulated in social media suggesting people to steam their used masks to disinfect them. This should not be done as the high heat will destroy the protective function of the mask, making it not possible for reuse.

2. Reuse masks

Surgical masks are medical consumables intended for single use. In dire straits however, putting a used mask in between two pieces of tissue paper for temporary storage and save for later use can be considered.  When doing so, please make sure the colored layer of the mask is not touched, and to perform hand hygiene immediately after putting the mask away.

3. Use of masks after expiry date

Expired masks can still be used, as long as the packing is intact and the environment for storage is optimum. Manufacturers however will not guarantee its quality beyond the expiry date.

To sum up, wearing the right mask in a correct way is an essential protective measure to fight against the virus

Dr Alexander Chiu, Medical Director, Health and Employee Benefits, AXA Hong Kong and Macau