Some Covid masks are better than others. I know

Nov 14, 2023

Cloth or surgical masks just don't cut it – respirators are far more effective, and they’re comfortable too

As a mechanical engineer with a background in aerosol science, I often wondered why months into the pandemic we were still using cloth masks. People used similar coverings during the Spanish flu pandemic in 1919, more than 100 years ago. I knew better mask technology existed, and people needed to know about it.

So I embarked on a year-long mission to test, document, and review the best masks I could find. This eventually entailed building a mini aerosol laboratory in my bathroom, with scientific instruments capable of measuring particles 1/50,000th the width of a human hair. I have a public database for my results. And a Youtube channel. Over time I began to be known as the Mask Nerd.

With the Omicron variant spreading around the world, the most common question I get is still the most basic: what kind of mask should I be wearing?

If possible, not a cloth or surgical one. These masks are moderately effective at capturing particles coming out of your own mouth – what we engineering nerds call "source control". But they offer little protection against incoming particles. We call this part – how well the mask protects the wearer – respiratory protection.

A typical cloth mask, while better than nothing, only provides around 30-60% protection to the wearer. Surgical masks, while better at 40-80%, lack a tight fit to the face, resulting in large amounts of leakage around the mask.

Much, much better masks exist. These are sometimes called high-filtration masks, or by the technical name of a filtering facepiece respirator. Such high-performance masks provide significant protection to the wearer at levels that are between five and 10 times that of a cloth mask, while also providing significant protection to others.

In fact, simply wearing a high-filtration mask can buy you significant time if exposed to infectious individuals. Analysis and studies suggest that with cloth or surgical masks, the risk of infection may increase within minutes of being around others with either no mask or low-performing masks. However with the use of well fitting, high-filtration masks, this same level of exposure would now take hours to become dangerous. However, it should be noted that being around a contagious person always carries some risk.Beyond the actual increased protection from potential exposure, these masks provide a psychological improvement in day-to-day life, as you no longer need to concern yourself with the fact that those around you may prefer to wear their cloth masks under their chin.

One might assume based on the technical name, "respirator", that these would be some Darth Vader-style headpiece – cumbersome and difficult to breathe in. However it's quite the opposite. These masks feature a high-tech material called electrostatically charged meltblown polypropylene (quite a mouthful). It features tightly spaced micron-sized fibres – about 1/50th the diameter of a human hair – that have an electrostatic charge applied to them to catch even smaller particles. This material can filter particles that are a just a few nanometres in size.

The most amazing thing, though, is that while providing nearly 99% protection from typical Covid respiratory aerosols, these materials also provide breathability that surpasses that of a typical three-layer cloth mask. When picking a mask you want to look at three criteria: filtration, comfort and fit. Respirators provide not only the filtration, but comfort from highly breathable materials, and a tight sealing to the face by the design of the mask.

This is what makes respirators such an easy option: you need not worry about anything other than finding one that fits your face. This ensures that all the air flows through the mask, not around it.In the EU and UK, the FFP2 standard is my recommendation for the general public. It features both ear-loop and headband varieties, comes in a variety of colours, and typically costs less than a pound. Regulator oversight by various EU and UK government bodies helps to ensure a quality product.

In the US, the common NIOSH N95 is a great option, but it is limited to headbands only. Ear-loop masks are available via other international respirator standards, such as the KF94 (in South Korea) or KN95 (China). However it should be noted that the KN95 is a self-reported test standard, and lacks strict government regulation by China, resulting in many underperforming and often flat-out fake masks. The KF94 is less affected by this, as it is regulated by the Korean equivalent of the FDA.In my year of testing nearly 100 different masks, I have found over and over again that there are high-performing masks that outperform cloth masks, while still featuring many things people like about their cloth masks.

Mask makers such as Masklab and Posh have created highly decorative designed masks, with bright colours and intricate patterns. Many KF94 masks feature built-in ear-loop adjusters, making for a comfortable, but tight fit. Other mask makers such as 3M – with the 9152 (9105 in the US), a mask that helps the wearer breathe as if there were none on their face, while also providing a full range of motion for the jaw – provide great options for singers and choruses.With ample supplies of these masks available and a more transmissible variant on our doorstep, there has never been a better time to up your mask game. I encourage people to go out and try a few different varieties, find what they like and what fits their face. With ample supplies of these masks available and a more transmissible variant on our doorstep, there has never been a better time to up your mask game. I encourage people to go out and try a few different varieties, find what they like and what fits their face. However, masks with exhalation valves should be avoided; these allow unfiltered air to escape and don't provide the high levels of protection to others that non-valved masks do.

Aside from helping individuals choose the best mask for themselves, I would also encourage governments to increase the domestic production of masks, which would not only create jobs, but also allow regulatory oversight and a supply of effective, safe masks for their citizens. And good masks should be provided free of charge to the many that may not be able to afford them.

Not all masks are created equal, so it's time to make sure everyone knows about high-filtration masks. These simple, inexpensive and super-effective masks can make a significant difference in our fight against Covid. If you wear a mask, you might as well make it count by wearing the best.

Aaron Collins is a mechanical engineer with a background in aerosol science who tests and reviews masks on his YouTube channel

This article was updated on 31 December 2021 to include guidance on avoiding – in the context of public mask wearing during the Covid pandemic – masks that have valves.