Back when the pandemic started, in the days when hand sanitiser and toilet paper seemed impossible to find, face masks were suggested to help stop the spread of COVID-19. Surgical masks and cloth masks were recommended for the general population to reserve stocks of hospital-grade masks for healthcare workers. Now, nearly two years later, our understanding of which types of face masks are best is changing as new waves and variants come along and shift the goalposts.

As we deal with the record-breaking numbers of Omicron infections, many countries are rethinking their COVID-19 mask advice for the community. With the heightened transmissibility of the more contagious Omicron variant, it’s now time to rethink and upgrade to wearing a high-quality face mask to slow the spread.

What is the current advice?

The Australian government recommends masks be worn to help protect you and those around you. They have left it up to individual state governments to mandate which masks are allowed and in what situations they must be worn. While different states have differing restrictions on how many layers a mask must be, the common requirement is for masks to be worn in high-risk situations, such as in hospitals, transport hubs and airplanes.

Do we still need masks when vaccinated?

We know that masks help limit the spread of COVID-19 by protecting against small droplets or particles that you could cough, sneeze, or breathe out and potentially infect someone with. Research has shown that it's possible to spread COVID-19, particularly the Omicron variant, even if you are asymptomatic or vaccinated.

Vaccinated people can still carry the virus, even if they don't have symptoms, and can still be contagious to others. For this reason, being vaccinated doesn't mean you no longer need to wear a mask. Research has found that a person with Omicron is able to infect more people than someone infected with prior variants. There are also so many cases in most communities right now that the chances of being around high levels of airborne virus has increased.

Authorities are also worried that people who have been vaccinated are at risk of seeing themselves as invulnerable and forgetting to take precautions. Mask wearing is an obvious reminder that the pandemic is far from over, and that basic precautions, such as social distancing and hand washing, still need to be followed.

Which is the most effective mask against Omicron?

The most effective masks against airborne particles are the hospital-grade masks – known as respirator masks. They are commonly called N95 or KN95 masks. In Europe they’re known as FFP2 masks, in Australia they’re also called P2 masks. These masks need to be certified to filter 95% of particles 0.3 microns in size and larger.

These masks have been used in hospitals and industrial situations to protect against infectious and toxic particles for decades. They are now being advised as the best protection against COVID-19’s Delta and Omicron variants.

At the beginning of the pandemic the stocks of these masks were difficult to source, and so it was declared that they should be kept for healthcare workers, who were at the greatest risk from the coronavirus, as they were dealing with highly infectious patients, as well as needing them for their regular pre-pandemic hospital requirements. Now that stocks are more plentiful, and Delta and Omicron are even more contagious than previous variants, they are being advised for the general population.

What are respirator masks?

Respirator masks are specialised filtering masks. Respirators are made to protect you by fitting closely on the face to filter out particles, including the virus that causes COVID-19. They can also prevent droplets and particles you breathe, cough, or sneeze out from escaping your mask, so you do not spread them to others.

Respirator masks are made of multiple layers of tough yet flexible non-woven polypropylene fibres. They're designed to make a sealed fit around your nose and mouth. Elastic loops secure the mask in place. These masks sometimes feature a valve to make inhalation and exhalation easier, but they're not required to qualify as a respirator mask. Respirator masks include the N95, KN95 and KF94 masks.

The filter material in respirator masks is usually a non-woven polypropylene electret, which means the fibres carry an electrical charge. This will help to enhance particle collection in the filters, while allowing increased breathability.

How do respirator masks work?

Respirator masks need to filter out very high percentages of tiny particles. The number in the mask’s name tells you what percentage they are certified to, so N95 and KN95 masks are certified to 95%, while KF94 masks are certified to 94%.

They must meet, or exceed, this percentage of particles that are 0.3 microns in size. This is the particle size for which the masks are the least effective. Interestingly, N95s are better at filtering out particles that are either larger or smaller than 0.3 microns. (keep this link)

A 2017 study published in the Journal of Occupational and Environmental Hygiene has shown that these masks can filter about 99.8 percent of particles with a diameter of about 0.1 microns. According to an April 2020 review published in the journal eLife notes, the virus that causes COVID-19, SARS-CoV-2, is an ‘enveloped virus’ with about a 0.1 micron diameter, meaning N95s are particularly suited to the current pandemic.

N95 vs. KN95 - What's the Difference?

The difference between N95 and KN95 respirator masks is which country’s standards they are certified to. The N95 masks are designed to US standards, the KN95 masks are designed to Chinese standards. Both are required to meet the the standard of 95% protection against all particles that are greater than 0.3 µm in diameter. While only N95 masks are certified to be used in US hospitals, when N95 masks were in short supply early in the pandemic, KN95 masks were approved for use. This emergency authorisation has ended now that stocks are available again.

The other big difference is in the look of the respirator mask – N95 masks have a more rounded appearance and attach with elastic that goes around your head. KN95 masks have a seam down the centre, which means that mask can be folded in half for storage.

Key Differences

1. KN95 certification: The Chinese standard requires the manufacturer to run a special mask fit test on real humans with ≤ 8% leakage. The N95 mask standard does not require manufacturers to run fit tests.
2. N95 certification: The US standard has slightly stricter requirements for pressure drop while inhaling. That means they’re required to be slightly more breathable than KN95 masks.
3. N95 certification: N95s also have slightly stricter requirements for pressure drop while exhaling, which should also help with breathability.

What are KF94 Masks?

Another form of respirator masks is the KF94. This is the respirator mask that follows the Korean standard. KF stands for “Korean Filter”. They are required to meet a minimum of 94% filtration efficiency for particles of 0.3 microns in size.

KF94 masks have grown in popularity since the start of the pandemic, largely due to their shape. The KF94 respirator mask features a tent-like shape that creates extra space between the mask and your mouth. The side flaps are contoured to your face to help close gaps, providing the filtration seal required to meet the standards for a respirator mask.

How is a KF94 mask different to a KN95 or N95 mask?

The main difference between KF94, KN95 and N95 masks is their shape. KN95 and N95 masks typically look a bit like a bird beak, sticking out from the face. A KF94 looks more like a surgical mask or cloth, with a flatter design.

KN95/N95 masks are rated with a 95% filtration efficacy and the KF94 masks are rated to 94% filtration. This is the minimum filtration at 0.3 microns, meaning masks that provide better than 94% filtration are still certified as KF94. Authorities say the 1% difference in standards is no reason for concern. Both still provide a substantial degree of protection from particles.

Should we use respirator masks with valves?

A valve in a respirator mask helps the person wearing the mask to breathe. Unfortunately, the valve reduces the filtration the mask provides to the exhaled air, meaning that it is depositing more unfiltered particles into the air for others to breathe in.

Are Respirator Masks Reusable?

KF94, N95 and KN95 masks are not meant to be reused. The multiple layers provide an electrostatic charge that helps to trap airborne particles. This charge is reduced by prolonged use. Some studies have shown that they can be worn more than once by spraying the respirator mask with ethanol, or decontaminating it with a sanitiser device, however they will still only provide effective filtration for a few wears.

Are there downsides to Respirator Masks?

The biggest downside to respirator masks is the price and limited availability. Now that they are recommended for use by the general public, demand is high, making them difficult to source.

As they are disposable, this adds to the cost, as well as the environmental impact. The guidelines suggest that a disposable mask should be sealed in a Ziplock bag and placed in the bin, adding both the mask and plastic to landfill.

Some claim respirator masks are less comfortable. This is due to the required seal against the face. To provide the level of filtration and protection this is an important feature of respirator masks. Note: this seal means that respirator masks are less efficient where facial hair prevents a proper seal.

The seal can also be difficult for children who are prone to fiddling with or adjust their masks regularly. Specific children’s size respirator masks are available, but can be difficult to find.

Are cloth masks useless now?

You’ve probably got a good supply of cloth masks and stores of surgical masks by now. So, what should you do? Don’t throw away your cloth masks. In low-risk situations cloth masks will suffice. For added filtration double-masking a cloth mask over a surgical mask can help by adding the contoured fit of the cloth mask to the added filtration of the surgical mask. This is a good alternative in lower risk situations, or when respirator masks aren’t available.

Cloth masks are getting a bad rap at the moment, and this, in part, is because there is no standard for cloth masks. A wide, open-sided masks made from 1 or 2 layers of scrap fabric is being lumped in with a contoured mask of high-quality materials.

Surgical masks are cheaper – can I just switch to those?

Not really. While some surgical masks may have better filtration capacity than cloth masks, they were primarily designed to prevent the emission of large droplets. The small infectious particles are not trapped by the surgical mask. In additions, the loose fit of surgical masks allows for air to escape around the edges. Now that the coronavirus is airborne these unfiltered particles will stay in the air for longer.

Comparing cloth masks, surgical masks and respirator masks

Research shows that a well-fitted respirator mask provides the most protection. Well-fitting surgical masks and less fitted respirator masks offer the next best protection, followed by cloth masks made with multiple layers. Single layer and loosely woven cloth masks are the least effective, but they can provide an additional layer of protection when worn over a surgical mask.

To illustrate the importance of wearing masks, a University of Minnesota study investigated the time taken for an infected person to transmit enough viral load to infect another person. The study looks at the difference if the infected person and the person they’re interacting with are wearing no masks, cloth masks, surgical masks and N95 masks. Cloth masks still provide an extra 12 minutes of protection than if they weren’t wearing masks at all. If they were both wearing surgical masks, it would take an hour to get infected, and if they were both in non-fit-tested N95s, the infection time would increase to just over six hours. The best protection comes if both people were protected with fit-tested N95s. The study shows it would take about 25 hours for transmission to occur. 

How to successfully double-mask

“Double-masking” is the term given to wearing 2 masks for added protection. To double-mask with a cloth mask and a surgical mask, secure the cloth mask over the top of the surgical mask. The added layers will help with filtration, while the cloth layer also helps secures the surgical mask with a tighter fit. It is best if your nose and mouth are both covered and there are no gaps at the top, bottom, or sides of the mask.

Double-masking isn't necessary with respirator masks, as they have superior fit and filtration. There is no harm double-masking a respirator mask if it helps you with the fit.

How to wear a respirator mask

A respirator mask should cover your mouth and nose with no gaps, especially around the nose and chin. To create a tight seal, ensure the nose clip is bent to the correct angle for your nose and the straps hold the mask on tightly. If the mask collapses a small amount when you inhale, the respirator should be working correctly.

When to wear which mask?

Unless you have an unlimited supply of respirator masks, you may want to swap between masks depending on where you are going. If you are going into a crowded location or high-risk situation, such as a hospital or public transport, a respirator mask is your best protection. If you are going to a low-risk location where social distancing can be maintained or there are low levels of COVID-19 in your community double-masking with a cloth mask and surgical mask should be sufficient.

Where to buy respirator masks

When purchasing your respirator masks, be aware that the increased demand has led to an increase in counterfeit respirator masks on the market. These look the same but don’t comply with the 94/95% filtration requirements. Be sure that you buy your masks from a reputable source.

Pharmacies are a good option, as they have access to reputable supply chains. Zoomlite has also been able to secure limited numbers of high-quality certified respirator masks. Check availability via this link.