When it comes to respiratory protection, are two masks really better than one?
February 10, 2021 | Published by Dr. Peter Maric, Physician
In Black Jack, doubling down can increase your winnings, but also your losses. However, when it comes to your health, gambling is not an option. Health organizations around the world such as the CDC, Health Canada, and the WHO, recognize the growing body of evidence of the airborne transmission of SARS-CoV-2, which is the virus that causes COVID-19. With new, more contagious variants appearing, the concept of “double masking” is being touted as a potential solution. So what does this mean, how does it work, and is it really a “risk free” option?
What is Double Masking?
One year into this pandemic, and we have all grown accustomed to wearing masks, and most of us recognize that not all masks are created equal. However, many people do not necessarily understand how they are intended to protect us, and how the different types of masks work. We previously discussed the difference between masks and respirators in a medical setting, and it is important to understand that masks are predominantly designed to contain the spread of the wearer’s exhaled respiratory droplets, while respirators are predominantly designed to protect the wearer from inhaling airborne particles, including infectious particles.
The idea of “double masking” is not new, but recently it became widely circulated after Dr. Anthony Fauci, the chief medical advisor to US President Joe Biden, recommended that “it just makes common sense”. However, many things in science and medicine intuitively make sense, which are later shown to behave differently than expected, because we fail to consider factors that may alter the outcome. Dr. Michael Osterholm, who also advises President Biden, has pointed out that with “masks that have an already compromised fit or filtration capacity” wearing two masks may actually exacerbate these problems, since air takes the path of least resistance, and will preferentially escape from any gaps. Harvard’s Dr Joseph Allen, argues that wearing a surgical mask plus a cloth mask over top can in fact “catch more than 90% of respiratory aerosols”. Unfortunately, we have not definitively answered the questions about the potential benefits, or the potential harms. That is an active area of research at the moment that is ongoing.
If the “double mask” becomes too difficult to breath through, people may not wear them as diligently, thus negating any perceived benefit. The idea of double masking seems to be gaining momentum in public circles, and with this in mind, the recommendation for double masking is to wear a surgical mask plus a cloth mask tightly over top. There is a global shortage of N95 respirators, and it is important to understand that without a proper fit, an N95 may not offer ideal protection for the same reason: air escapes around the edges of the mask, thereby bypassing the filter material. Thus, rather than acting as a respirator, it behaves more like an expensive mask, falsely reassuring the wearer, and taking important resources needed for the frontline out of circulation. For double masking to work as intended, you need to have an excellent seal to the face, coupled with a highly efficient filter material, whilst still maintaining breathability.
O2 – Ahead of the Curve
When I first began working with O2 at the beginning of the pandemic, I was looking for a solution to the supply chain issues around disposable N95 respirators. I immediately began testing and modifying the O2 Curve, which is a compact elastomeric respirator originally designed for air pollution. One of the first things we did was to create a surgical mask adapter, specifically designed to allow any individual to wear their O2 Curve under a surgical mask. We also designed the adaptor to minimize contamination of the Curve, as well as to ensure that we captured exhaled respiratory droplets from the exhaust valves. In doing so, we needed to ensure that the breathability was not significantly compromised, and we are currently using everything we have learned from this process to design a made for purpose medical respirator we expect to launch this year.
There are two important things to understand in relation to the O2 Curve and “double masking”.
First, the O2 Curve is an elastomeric respirator, meaning on its own it is a viable option for protection. When the O2 Curve is worn with a Max Air filter, and the valve plugs, it can provide a high level of filtration and protection. In fact, because the Curve uses a medical grade silicone seal, it is able to form an airtight seal to the face, and the issue of air escaping around the filter is dramatically reduced; which is a feature that both surgical and cloth masks don’t provide.
Secondly, the O2 Curve already has added features that allow double masking to be both comfortable and effective. As was just mentioned, the valve plugs were designed to plug the exhalation valves which transforms the respirator from providing a one way level of protection to a two way level of protection. However, in the case where the exhalation valves of the respirator are exposed, the surgical mask adapter can be used in place of the valve plugs. The surgical clip is an accessory that many may want to consider now that double masking is being highly encouraged.
So, two masks can be better than one, but it all depends on what you are wearing, and how you integrate them together. Provided you do not significantly reduce breathability, and maintain a tight seal on the face, two masks may absolutely be of benefit. At present, the efficacy of “double masking” is being recommended by some, but with important caveats that should not be ignored. The double masking trend has begun with a “function over fashion” approach. However, if you choose the right mask(s), and wear them properly, the evidence clearly demonstrates that this is one of simplest practices that we can engage in on a regular basis to help protect ourselves, and others, from the spread of COVID-19.