Thursday, December 05, 2019

HK CDW: Surgical Masks For Respiratory Protection

Photo Credit PHIL (Public Health Image Library)


Last month, in The WHO NPI Guidance : Personal Protection, we looked at the World Health Organization's guidance on NPIs - Non-Pharmaceutical Interventions - during an influenza pandemic or severe flu season. 
Interventions that included hand hygiene, respiratory etiquette, and the use of (surgical) face masks.
While recommending that symptomatic flu cases wear surgical masks to reduce the chances of infecting others in any epidemic or pandemic, the WHO held back on (conditionally) recommending the public wearing of surgical face masks to protect the wearer in anything less than a severe pandemic or epidemic.

Long time readers know that over the past decade we've looked at a number of conflicting studies on the effectiveness of surgical masks in protecting the wearer - most recently, last September - in JAMA: N95 Respirators vs Medical Masks for Preventing Influenza.

This JAMA study suggested that here was little practical difference in infection rates between HCWs who wore either type of respiratory PPE over several flu seasons following the 2009 pandemic.
But other studies, have come to different conclusions.
While this debate will likely go on, in Asia, the wearing of surgical masks by the public during cold and flu season is ubiquitous, and is often encouraged by public health officials - regardless of the severity of the epidemic. 

With flu season expected to ramp up soon in Hong Kong, the latest issue of the CHP's Communicable Disease Watch features a tutorial on the wearing of surgical masks by the public to protect against respiratory diseases.

First a look at their advice, then I'll return with a postscript. 

Prevention of infectious diseases by wearing surgical masks

Reported by Mr Anthony NG, Senior Nursing Officer, Ms Jane LEUNG, Advanced Practice Nurse and Dr Leo LUI, Associate Consultant, Infection Control Branch, CHP.

Many respiratory tract infections (including influenza) are mainly spread by droplets produced when people cough, sneeze or talk.

These infections have the potential to cause serious illnesses especially in high-risk individuals. In addition to adopting a healthy lifestyle and practising basic infection control measures such as hand hygiene, cough etiquette and environmental cleanliness, proper use of surgical mask is also an effective means to protect individuals and the public against respiratory infections.
What is face mask?
Face mask provides a physical barrier to fluids and large particle droplets. Surgical mask is a type of face mask commonly used. When used properly, it can prevent infectious droplets containing respiratory pathogens from entering our mouth and nose. Individuals should wear a surgical mask when(1) they have respiratory infection; (2) need to care for a person with respiratory infection; or (3) visiting clinics or hospitals during peak season of influenza. Individuals at high risk of having infection-related complications may also consider putting on surgical masks when visiting crowded or poorly ventilated public places.
Most surgical masks adopt a three-layer design (Figure 1) which includes an outer fluid-repelling layer, a middle layer serving as a barrier to germs, and an inner moisture-absorbing layer. Wearer should follow the manufacturers’ recommendations (if available) when using surgical mask, including proper storage and procedures of putting on surgical mask.
Points to note on wearing and removing a surgical mask:

✦ Choose the appropriate mask size. Child size is available for selection as indicated;
✦ Perform hand hygiene before putting on a mask;
✦ The mask should fit snugly over the face;
✦ Avoid touching the mask after wearing. Otherwise, should perform hand hygiene before and after touching the mask.
Putting on the mask:
✦ Determine the orientation of the mask. In general, the coloured side should face outwards with the metallic strip on top (Step 1). For masks without a coloured side, the side with folds facing downwards should face outwards, with the metallic strip on top.
✦ For tie-on surgical mask, secure the upper tie at the crown of head. Then secure the lower tie at the nape (Step 2). For ear-loops type, position the elastic bands around both ears.
✦ Extend the mask to fully cover the mouth, nose and chin (Step 3).
✦ Mould the metallic strip over nose bridge and the mask should fit snugly over the face (Step 4).

Figure 2 - How to wear a surgical mask. (Source: The Centre for Health Protection of the Department of Health.
Available from
Removing the mask:
✦ For tie-on surgical mask, unfasten the tie at the nape first; then unfasten the tie at the crown of head (Step 5). For ear-loops type, hold both ear loops and lift the mask gently off the face. Avoid touching the outside of the mask during removal as it could be contaminated.
✦ After taking off the surgical mask, discard in a lidded rubbish bin and perform hand hygiene immediately.
✦ Surgical mask should be changed whenever damaged or soiled and at least daily.
(Video available from
Proper wearing of surgical mask can protect individuals and reduce the risk of acquiring respiratory tract infections. Apart from
that, the following preventive measures should also be emphasised:

  • Perform hand hygiene frequently and properly especially before touching eyes, nose and mouth;
  • Maintain respiratory etiquette/cough manners;
  • If develop symptoms of respiratory infection, put on a surgical mask and seek early medical attention;
  • Stay home to rest and avoid unnecessary social contact until recovery;
  • Persons at a high risk of having infection-related complications, e.g. pregnant women or persons with chronic illnesses are advised to receive influenza vaccination before start of the flu season to prevent seasonal influenza infection. It takes about two weeks for antibodies to develop in the body after vaccination. Medical advice should be sought promptly if influenza-like symptoms develop so that appropriate treatment can be initiated as early as possible to prevent potential complications.

Admittedly, the wearing of surgical masks in Asia is as much of a cultural phenomenon as it is a public health precaution. Its roots go back at least 100 years, to the 1918 pandemic, when everyone who could get a mask was wearing one.

The pandemic eventually ended, but in 1923 Tokyo was struck by a M7.9 earthquake that left Tokyo in ruins and killed – by some estimates – more than 140,000 residents.
The timing of the 1923 quake, at lunchtime, meant many people were cooking over open fires when it struck, and that – combined with winds from an offshore typhoon – contributed to the firestorm that swept Tokyo.
Once again, surgical masks became a popular accessory, to filter out the smoke and ash the lingered for months following the quake. Reinforced over the years  by SARS, bird flu, air pollution, and life in densely populated cities, the wearing of surgical masks in Asia has become commonplace.

While Americans and Europeans are unlikely to adopt this practice in anything short of a severe pandemic, it does make sense to keep a small stash of surgical masks in your emergency supplies. 
  • If you are sick, you should don a mask before venturing out in public - particularly when going to doctors or health clinics -  in order to reduce transmission to others. 
  • Judicious use of a mask when you are sick could also help to reduce transmission to other members of your household, or to your care giver. 
And if you happen to be a caregiver to someone in your household, it wouldn't hurt to slip one on when you are in close contact with a sick individual.  Doubly so if you suspect your patient could have norovirus.

I keep a couple of boxes of surgical masks with my preps, and I consider it good insurance. While I wouldn't consider it anything close to being fully protective, anything you can do (getting vaccinated, practicing good hand hygiene, avoiding crowds, etc.) to reduce your odds of getting the flu is a good investment in your health.