After recently reviewing silicon-based face masks such as the O2 Curve Respirator and Gill Mask I received some requests to review another silicon-based face mask – the S2 face-mask from MoD (Medical on Demand).
This mask is rather unique in that it uses FDA approved, biocompatible silicone. It is also produced to the EN 14683 Standard (European Standards) and holds Type IIR certification, indicating that it has a bacteria filtering effectiveness of > 98% and is splash-resistant.
This, along with the filtration testing of the filter, makes the MoD S2 one of the more tested masks on the market. Combined with the unique design of the S2 mask, I quickly became interested and wanted to test the mask myself.
At first glance, this mask looks very unique compared to other masks on the market. This unique design brings with both advantages and downsides. However, one thing is certain – the MoD S2 is a very unique face-mask.
In this review of the MoD S2 mask, I will share both my personal experiences with the mask and the science and lab testing behind it. I will begin by covering the more important aspects of filtration specifications and fit before moving on to less important elements such as the lifespan and design (looks).
This post contains affiliate links. For more information, please refer to my affiliate disclaimer. I was sent a product for review, but the article is not sponsored. All opinions expressed in this post are my honest thoughts. I only recommend products that I genuinely believe in.
Information on this blog is for informational purposes only. Readers are encouraged to confirm the information herein with other sources. Furthermore, this information is not intended to replace medical advice from professionals. This website assumes no responsibility for the accuracy of the information, and information is subject to change without notice. Devices mentioned on this website are not medical devices and do not guarantee protection.
The filter used on the S2 uses a five-layer design that includes both a traditional melt-blown layer and an active carbon layer. It’s important to note that information in this section applies not to the mask, but to the filter. Therefore, it’s important to make sure the filter is fitted correctly in the face-mask, and that the mask creates a seal.
MoD PPE has some of their certifications (from SGS, Nelson Labs and EN Standard) available on their website. Further information and full test results are available on request. The results that I will be focusing on in this section are those provided by SGS. At the time of this review, I was not able to view the Nelson Lab certificates.
The tests carried out by SGS assessed the conformity of the filter with the EN 13274-7:2019 standard. These filtration tests are carried out using sodium chloride particles with a median diameter of 0.06μm to 0.10μm (60 to 100 nanometer) (source). Although the mask does not adhere to this standard, the filtration results are provided below.
The second test is carried out using paraffin oil with particles between 0.29μm and 0.45μm (source). Paraffin oil tests are carried out to represent oil particles, whereas NaCl (sodium chloride) tests represent filtration against the standard, non-oil particles.
*All percentages given are the worst-case among three tests.
Both of these tests were carried out at a flow rate of 95 l/min. This is the standard flow rate for testing and represents a flow rate higher than most adults will breathe – even during heavy exercise. If we inverse the penetration percentages above, we can see the overall filtration of the filter media.
*All percentages given are the worst-case among three tests.
With these being the worst-case results across three filtration tests, we can see that the filter used in the S2 is a relatively capable filter. The testing carried out by SGS at 0.06μm to 0.10μm is using a smaller particle size than is often used during filtration testing.
The mask also is certified certified EN 14683:2019 Type IIR, a rating for surgical masks. This means that is has > 98% filtration for bacterial particles and is splash resistant. It is important to remember, however, that no mask guarantees protection and that smaller particles may penetrate.
Also worth mentioning about the filter is that it contains a valve in the centre. This valve will decrease breathing resistance and decrease humidity (and heat) within the mask. However, it also means that only air exiting the S2 face mask will be filtered. If you require two-way filtration, you can use the included valve-cover.
The filter also contains an active carbon layer. Active carbon is used to filter some volatile organic compounds (VOCs) and also to reduce some odours. The addition of a carbon filter provides benefits with almost no downsides.
The biggest strength of silicone masks is the fit. While cloth masks are often cheaper and look more fashionable, silicone masks generally provide a superior fit with a stronger seal.
Since only air that passes through the filter media is filtered, it’s vital to ensure that whatever mask you are using fits well and has minimal leakage (ideally, no leakage). This is something that is often put second to filtration. However, it’s just as important.
Silicone masks tend to fit better than cloth masks because they are more adjustable (especially around the nose, where many cloth masks use wire nosepieces), and because they can be worn more tightly since silicone is softer on the face. Typically, silicone masks also use head-band designs rather than ear-band designs and this allows for a more secure fit.
The S2 mask, in my experience, provided a good fit with minimal leakage. The mask sits under the chin, creating a seal a few centimetres behind your jawline. It then seals over the nose, between your eyes. From my experience, the most common leakage points are around the nose and on the cheeks.
When donning the mask for the first time I did find leakage around my nose. However, this appears to have been an issue with the upper headband being too loose as I have since adjusted the band and I haven’t noticed any leakage since.
Upon initially fitting the mask I did also encounter some issues with the inner filter piece popping out of the silicone shell. This created a gap between the silicon shell and my cheek. However, after a few attempts I managed to get the filter piece properly fitted and it hasn’t popped out since.
Since fixing these initial issues with the MoD S2 I have noticed very little to no leakage. The area around the nose is also very soft, and I felt less fatigued after wearing this mask compared to other silicone masks that I have tried.
As mentioned previously, the S2 relies on a dual-headband design. I am a big supporter of headbands on masks and I believe that every mask should use headbands rather than ear bands. Not only does it remove the strain on your ears, but it also creates a much sturdier fit for the mask, making it less likely to move over time.
One of the biggest issues that I have found with the silicone masks that I have tried is the breathing resistance. Typically, the larger the surface area of a filter the lower the breathing resistance. In other words, a smaller filter makes breathing harder while a larger filter makes breathing easier.
While there are other factors in play (filter material, filter depth, etc), the filter size is very important for breathing resistance. With both the O2 Canada Curve 1.2 and Gill Mask I felt breathing significantly more difficult than with a cloth mask. However, with the S2 I felt the difficulty of breathing was very similar to that of a cloth mask.
I believe this is due to the large size of the filter and the fact that it sits right in front of your mouth. With the Gill Mask I wrote that I felt like I was wearing a diving mask and that breathing was difficult at times. While the S2 still reminds me of wearing a diving mask, the breathing is much easier.
The S2 mask features a valve that can be covered with an included cover. Interestingly, I didn’t find the breathing resistance that different between wearing the mask with the valve covered and with it opened. I did, however, notice that the mask leaked a bit around my nose with the valve closed – something that didn’t happen with the valve opened.
One of the biggest benefits of silicone masks is the ease of cleaning and sterilization. This can be difficult on cloth masks as many cleaning methods reduce filtration (on masks without removable filters). Further, cloth masks require drying which can take hours or days.
Silicone masks, on the other hand, can be sterilized and washed within minutes in many different ways. This won’t harm filtration as the filter can be easily removed. Further, since the masks are made from plastic it’s very easy to dry them with a tissue or towel! This means that the MoD S2 mask can be quickly sterilized and reused.
This also means that the S2 mask is more environmentally friendly than many other masks on the market. The only part that needs to be regularly replaced is the filter, and even the filters are smaller than they are on nearly every other mask (with the exception of Gill Mask).
The S2 face mask uses a fully plastic design. There are three main parts, the shell, the filter-holder, and the headband. These all come separate, and within about 3 minutes they can easily be put together and the mask can be ready to go.
The outer shell of the mask is large and will cover almost all of your cheeks as well as your nose. While the size may put some people off, it does allow for a great fit. Along the bottom of the of the mask (near where your mouth is) there are holes in the plastic – the filter sits behind these holes and air flows through them.
In the middle-bottom of the mask you will find a valve. This valve can easily be blocked with a valve-cover that comes included in the box. I appreciate how MoD lets the user choose whether or not to use the valve based upon their situation.
Inside the silicone shell sits the filter-holder. This is a long piece of plastic with three sides (think of a half-hexagon). The valve is placed at the front side of the filter-piece and sits directly in front of the wearers mouth. The filter covers nearly the breathing area, and I believe this is what leads to the relatively low breathing resistance.
The filter is placed on the filter-holder which then sits in some grooves on the inside of the silicone shell. I found this method of filter replacement both relatively simple and convenient – I didn’t need to read the manual as it just made sense. The filter also seems to stay in place and I had little need to readjust it once placed in the mask.
Lifespan & Cost
The S2 mask itself is the biggest investment that you will need to make if you want to purchase this mask. The mask goes for €30 and as long as you look after the mask, it should last for years. The mask kit (€30) also comes with 10 filters – worth €15. This means that effectively the mask costs a very reasonable €15.
Filters for the S2 face mask are some of the most affordable that I have seen and I wish that more companies would provide such affordable filters. Typically, many companies sell filters in the $5-$10 per filter price range.
Since S2 filters are quite small and are designed to be simple, 10 filters can be purchased for €15 (with further sales at times). If worn for pollution protection, each of these filters can be used for 1-2 weeks or until breathing becomes difficult.
However, when sterile conditions are needed it is recommended by MoD PPE to change your filter after every use. They also recommend that the filter should be changed after visiting crowded spaces – such as after using public transport or a plane.
Finally, MoD offers a 50% discount for front-line workers. If you have believe that this mark is a good choice, then you can contact MoD at [email protected]. After providing verification, the company can give a discount on all S2 products.
Whether the S2 face-mask is the best mask choice for you depends on how you want to use the mask and your own personal requirements. However, I hope that this review has given you enough information to make a more informed purchasing decision.
With that being said, I do have some concluding remarks to make. Overall, I have found the S2 to be a great mask from my experience. It’s affordable, fits well, has relatively low breathing resistance, and is very easy to clean and sterilise. Of course, no face-mask is perfect and there are some flaws.
Personally I found the mask to be a bit big for me to want to pick up for typical daily wear. I would turn to this mask more when I know I need a mask that is comfortable for long periods and that provides high filtration – perhaps when the pollution is very bad (as it often can be in Seoul) or when taking a plane.
The ease and relatively low cost of replacing filters also make this mask a good choice for anyone that needs to regularly replace filters. The ease of cleaning the mask also adds to this, making the S2 face-mask one of the best reusable masks.
The mask is also supported by third-party lab testing and adheres to the EN 14683 Standard and has been tested by SGS and Nelson labs. This makes it one of the more tested silicone masks and filters on the market. If you are interested in trying the S2 face-mask, please check the link below.
Does the S2 Have an Official Rating?
The S2 face-mask does not have an official rating. However, it has filtration testing by third-party laboratories and has been shown to have over 99.6% particle filtration.
Where Can I Buy the S2 Face-mask?
Is the S2 Lab Tested?
Yes. The S2 face-mask has been tested by Nelson Labs and SGS.
What Filtration Does the S2 Face-mask Have?
The S2 face-mask has over 99.3% filtration when tested with paraffin oil and over 99.6% filtration when tested with sodium chloride.
Is the MoDPPE S2 Better Than Gill Mask?
I found that the S2 face-mask fit me better than the Gill Mask and it also had lower breathing resistance. However, the Gill Mask is more versatile as it can use more filters and it’s also a bit cheaper. The better mask really depends on your individual needs.
Is the MoDPPE S2 Better Than O2 Canada?
I found that the S2 face-mask provided a bitter fit that the O2 Canada Curve 1.2. However, the Curve is a much smaller mask and some people may find it more comfortable. It’s also significantly more expensive.