Health x Wellness

Healthcare Round-up: Wearing masks

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We share a short summary of the context and guidance available around wearing masks as the COVID-19 pandemic continues.

A study published in the journal Science has seen 39 scientists from 14 countries demand recognition that by improving indoor ventilation systems, it can help to prevent infections. This group is asking the WHO to extend “…indoor air quality guidelines to include airborne pathogens…” and to mandate “…building ventilation standards (need) to include higher airflow, filtration and disinfection rates, and monitors that allowed the public to observe the quality of air around them.”

There has also been research supporting the role aerosols play in spreading the COVD-19 virus. These reports have also contributed to recommendations about mask-wearing in public, and also safety distances.

Recently, the WHO and the US Centers for Disease Control and Prevention have accepted that the coronavirus can spread through the air. This point was in contention for a period, with the main mode of transmission being through proximity and surfaces. With the inclusion of possible airborne transmission, this means that even enclosed indoor areas that are not crowded can be considered hazardous.

Updated guidance for wearing masks in Singapore

With the updated guidance, there have been updates to official recommendations. In Singapore, health authorities have recommended the public to wear masks with better filtration capability.

In particular, if you are going to an enclosed space with people in close proximity, make sure you wear a mask with high filtration capability. That is important because of the latest evidence about the nature of the various strains, how transmissible they are and the fact that the spread can happen through aerosolised particles.

Lawrence Wong, co-chair of the COVID-19 multi-ministry task force

We round-up several resources to help better understand mask-wearing for better effect.

What is filtration efficiency?

Filtration capability refers to how well a mask can filter respiratory droplets. These droplets might contain bacteria or viruses and prevent them from passing through.

How do you measure a mask’s filtration efficiency?

Look for both the particle filtration efficiency (PFE) and bacterial filtration efficiency (BFE) measurements. PFE measures the ability to prevent aerosols from escaping. The BFE measures the effectiveness of filtering bacteria-containing droplets. 

A mask must have a BFE or PFE of at least 95 percent to meet the medical and surgical standards requirement. This means it is able to prevent at least 95 percent of such droplets from passing through the mask.

Another point to note is that reusable masks have a finite lifespan and need to be replaced after being washed and reused beyond a fixed number of times. Due to frequent use, the filtration capability might lose effectiveness.

Source: Straits Times

What is the ASTM rating?

Infectious diseases expert Leong Hoe Nam shared that there is an ASTM rating for masks. These ratings are issued by ASTM International. To obtain ratings, the masks are tested for bacterial and particulate filtration capability and fluid resistance, among other things.

These ASTM mask gradings range from one to three. All three levels can filter particles of 0.1 micron and above.

Source: CNA

How do I choose a mask?

The mask should have at least 2 to 3 layers of fabric including a water-repellant outer layer, middle filter layer and absorbent inner layer. The middle layer removes particulates and the inner layer absorbs droplets from the wearer’s mouth.

It’s important for the mask to have an appropriate fit around the face and chin and completely cover the mouth and nose, as well as allow for breathing.

Source: What you need to know about masks by Health Sciences Authority

Should I wear a mask when exercising?

It is not recommended to wear a mask during vigorous physical activity because it will reduce breathing capacity. However, try to maintain a 1 metre distance from other people, and if indoors, ensure adequate ventilation.

Source: WHO

wearing masks

What masks are not allowed under new guidelines?

Masks with exhalation valves do not effectively prevent the release of droplets from the wearer when he or she exhales. Plastic spit guards and face coverings such as neck gaiters, bandannas, scarves or handkerchiefs are not considered masks.

According to MOH, research has shown that face shields are not as effective as masks in protecting the wearer from droplet infection. They also do not adequately prevent droplet spread from the wearer.

Source: CNA

List of Singapore-based licensed manufacturers that produce surgical that meet 95 percent bacterial filtration efficiency

Here’s a list compiled by TODAY that shows Singapore-based (local) manufacturers that produce masks that meet the 95 percent BFE measurement.

In addition to the sources shared earlier, the following websites are provided for further references:

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