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UNMASKING THE TRUTH ABOUT MASKS — Filtering Efficacy, Proper Wear, and Best Cloth Masks

Updated: May 29, 2023

* This article is a summary of COVID--19 information available as of March 2020. Since then, the issue of mask supply has been eliminated and we have many tested and effective masks available for general population use. In addition, many studies have proved mask effectiveness in prevention of COVID--19 spread. The importance of mask effectiveness and mask proper wear still remains crucial.

* November 2021 update: New recommended masks are added at the end of the article.

white face mask

Amid #coronavirus pandemic starting to spread in the US, lots of people are focusing on masks as means to protect themselves from the novel virus. To wear or not to wear, that is the question many are asking.

Majority of stores already faced an ongoing shortage of masks that are flying off the shelves. Even the mighty Amazon proved to be no match for the current mask demands. Recently, they suspended many seller’s accounts for price gouging of masks and other COVID19 related products, which goes against their fair pricing policy. Global supply chains in general have been severely affected by the ongoing pandemic on the global level. Masks are almost impossible to come by. But do we really know what we are doing when it comes to stocking up and hoarding them or even how to properly wear them?

The current situation of global pandemic is new enough that reliable, scientifically studied information is hard to come by. We are learning more about the virus and effective means of protection every day and this can be confusing to many. Hence (and since many of you have asked), I put together this summary of scientific data we have at present time regarding this topic. With understanding that some information might change moving forward as this is a new and developing situation, the goal of this article is to provide summary of currently available information to help you make the best informed choices for yourself and your family.

So, what really is the situation with masks, what does the science say about their efficacy, proper wear, and what are the current issues surrounding them? Let's take a look...

Mask Shortage

Currently, there is a huge mask shortage, needed just for US healthcare workers, that can have disastrous consequences in effectively fighting the virus outbreak. Hence, it is irresponsible for healthy individuals to stockpile the masks that health workers use.

Thanks to inadequacy of US emergency preparedness, we are already facing a huge shortage of masks needed just for US healthcare workers. As reported by Time in February 2020, in case of a serious outbreak US hospitals would be 270 million masks short. The mask shortage is shocking, especially taking into account that the outbreak is still in very early stages in the US and experts agree that the worst is yet to come. It comes as no surprise that the main manufacturer of masks is China and they are currently struggling to keep up with their own demand. WHO (World Health Organization) warned us a month ago that stockpiling the masks by the general population is interfering with effective fight against the outbreak.

Hence, the shortage is probably the most compelling reason not to stockpile the masks, respirators, and other personal protective equipment that healthcare workers and first responders use. If our healthcare workers don’t have adequate personal protective equipment to protect themselves and their patients from COVID19 and from other serious, infectious diseases (that are infamously rampant in hospital settings), the consequences of COVID19 spreading like a wildfire could be exponentially disastrous.

Proper Mask Use

In order for a mask to work it has to fit properly (no children and no people with beards can wear respirators, for example), to be changed or cleaned on regular basis, and not to be touched by hands or constantly taken on and off. In addition, just wearing a mask is not enough to protect you from the virus. We still have to be vigilant about social distancing (from sick people and crowded places), staying home when we are sick, and proper hand washing (20 seconds minimum).

Mask Fit

In order for masks to be the most effective, they have to fit properly on your face. Many healthcare workers get professionally fitted for their masks and respirators, something that none of us regular people are able to do. Additionally, according to the FDA, N95 respirators for example, are not designed for children and people with facial hair. Experts agree, improper fit decreases mask effectiveness significantly.

Single Use

Masks used in healthcare setting, like surgical masks and N95 respirators, require frequent change. This is because moist air that you breathe out will make the mask damp, which will make it easier for pathogens to “stick” onto the mask. According to the FDA: “All N95 respirators are labeled as "single use", disposable devices. If your respirator is damaged or soiled, or if breathing becomes difficult, you should remove it, discard it properly, and replace it with a new one.” And let’s face it, with the current shortage, there is no way you will be able (or should be able) to stockpile enough to follow these recommendations.

Proper Handling

Masks also have to be put on and taken off properly. WHO has a whole page dedicated to how to do this. Before and after touching the mask you should always wash or disinfect your hands, otherwise germs from your hands will transfer to the mask. This is why with prolonged mask wear it is very important to take it off and put it back on properly, when you eat, drink, blow your nose, etc. I also see people wearing a mask over their mouth but not over their nose, or taking a mask on and off when they are talking, which defeats the whole purpose of wearing one. Every time you do this, you increase the likelihood of transferring germs from your hands onto the mask and decrease mask effectiveness.

I’m wearing a mask, so I’m fine

According to infection prevention specialist Dr Eli Perencevich there is also an issue with false sense of security that some people have from wearing a cloth or simple surgical mask, which is not as effective as N95, for example. This often decreases frequency of hand washing and other protective measures, like coughing in your sleeve, staying away from sick people, staying at home when you are sick, etc. Few weeks ago at an airport, I saw a woman with a mask coming out of a bathroom stall and then walking straight past the sinks without washing her hands. Whaaaat?!

Realistic Wear

Many N95 respirators that are highly effective against viruses are difficult to wear for an extended period of time, they quickly get hot, damp, and uncomfortable.

Loose fitting surgical masks are primarily meant to protect the patient from the doctor. And for the purpose of protecting wearer from virussized particles, respirators like N95 are often used. While N95 are highly effective at filtering viruses and other extremely small particles, they are difficult to breathe in on a long term basis. Dr William Schaffner, professor of preventive medicine and infectious diseases at the Vanderbilt University School of Medicine admits himself to not being able to wear it for more than 30 minutes. This is because N95 respirator without a valve can get hot and moist quickly (even 3M mentions this see image below from 3M website about N95 without and with a cool valve).

N95 with a cool valve is a better choice, as we can see from the image above, but valve can potentially let some infectious particles out, which can decrease protection from a potentially infected wearer.

In addition, N95 respirators without valves partially recirculate exhaled carbon dioxide, which can be problematic for people with reduced lung function. According to researchers at Stanford University N95 masks are "are estimated to reduce oxygen intake by anywhere from 5 to 20 %. That's significant, even for a healthy person. It can cause dizziness and lightheadedness."

According to the FDA: “People with chronic respiratory, cardiac, or other medical conditions that make breathing difficult should check with their healthcare provider before using an N95 respirator because the N95 respirator can make it more difficult for the wearer to breathe.”

And according to CDC: "Face masks should not be placed on children under the age of two, people with disability who cannot wear a mask, or who would not be able to remove the mask without assistance, and people for whom wearing a mask would create a risk to workplace health, safety, or job duty".

Mask Effectiveness

Not all masks work for filtering particles as small as viruses. Mask filtering efficacy is crucial in level of protection it will provide and hence needs to be taken into account when choosing which mask to wear. Check the graph below to see which tested masks are the most effective.

No surprise here, not all masks are created equal when it comes to effectively filtering particles as small as viruses. COVID19 has an average size of 0.125 microns. Below is a comparison of different particle sizes, for better understanding of what this means.

So before buying a mask or a respirator you should have the following information:

What particle sizes do they filter?

How effectively does a mask filter the virus?

  • Below is a chart showing effectiveness of different tested masks in filtering virussized particles, while being worn on an actual face. As you can see, some of them are pretty useless and some do a great job. Interestingly, some PM2.5 masks that are marketed as pollution masks for everyday wear, for general population, like Vogmask and ICanBreathe, tested really well for capturing virussized particles. This is impressive and encouraging! And some other popular masks, like Japanese Pitta mask are, well... pretty much useless for this purpose. This is not that surprising considering that Pitta masks are advertised for protection against pollen and dust.

CONCLUSION: Choosing to Mask

As per WHO recommendation, you should always wear a mask if you are sick, to protect the others (family members or when going outside). Surgical masks are made to primarily protect a patient from doctor’s germs, hence they work well in this case. If you are taking care of a person who is sick with COVID19, you should wear a wellfitted, independently tested KN95 or N95 to protect yourself. If you work in a highrisk job, such as healthcare, essential worker, or a similar consumer facing job, wearing a good fitting, effective mask will dramatically decrease your risk of infection. As per FDA recommendation people with compromised immunity and preexisting conditions should consult their doctor as regular mask wearing may be highly recommended for them.

Scientists estimate that COVID19 can spread most effectively within 3 to 6 feet from a sick person who is coughing, sneezing, or talking. Hence, wearing an appropriate mask in crowded public places during an outbreak makes sense (public transportation, airplanes, large or dense social gatherings like church, sports events, concerts, busy office, etc.). Although, during a significant community spread in your area, you would do yourself a favor and avoid places like these as much as possible.

Criteria for Good Mask

So after deciding that a mask is the right choice for you, which one should you pick? Here are some of the criteria that we are clear on so far:

  • Do not use masks used by healthcare professionals If you are healthy, not taking care of sick person, and do not work in highrisk setting, please stay away from N95 respirators. Thank you.

  • Filtration Use masks with confirmed, independentlytested performance for filtering virussized particles (see the chart above). Some of the reputable testing agencies include Nelson Labs, CDC and its division NIOSH, and ECRI.

  • Breathability — Ease of breathing is a very important consideration especially for prolonged wear. Respirators like N95 are not a viable longterm choice for general population for more reasons than one. While wearing a mask, you should make sure you can breathe comfortably so that you refrain from frequently taking a mask on and off, or just throwing it in the garbage in frustration.

  • Fit — Good fit is a must to ensure promised filtering efficacy. If a mask doesn't fit your face well and leaves gaps on the sides or around nose or chin, the filtering efficacy will be significantly lower. So pick a mask with adjustable nose piece, adjustable ear straps or chin tabs for the optimal fit and comfort.

Below is the list of recommended brands that, based on our research, fit all the above criteria. In our opinion any of these masks would be a great choice.

LIVING PUR Masks Recommendation

  • Cambridge Mask — This UK made mask uses some impressive filtering technology developed by US Ministry of Defense for military purposes and it has particle filtration efficacy of >98%. According to the company's website, the mask meets US N99 standard (for 99% filtration) and EU FFP2 standard (report). It is affordable at £25 or $32 and lasts around 340 hours on average. It can be hand washed with warm water and soap. The company ships worldwide and it is certified safe for children age 3 and up. This mask is comfortable to wear and it does not stick to your face when breathing or talking. If it is well fitted on your face it will not fog eyeglasses.

Cambridge mask for covid
Cambridge mask
  • Vogmask Based on independent testing done by this mask, from San Francisco company, is 95.2% effective in filtering virus—sized particles. According to company's website Nelson Lab testing confirmed filtering efficacy of >95% for 0.3 micron particles, which conforms to the NIOSH N95 criteria (report). The mask is affordable at $33 for the fact that it can last several months. This mask is also the most stylish out of the bunch, with many patterns and sizes from S to XL available. It can be hand washed with warm water and soap. The mask is comfortable to wear but it can sometimes stick to the face when talking and also fog the eyeglasses.

Vog mask for covid
Vog mask
  • As mentioned above, if you are taking care of a sick person or work at high—risk job 3M N95 respirators are the safest and the most effective choice.

  • There are some other masks that claim to be highly effective in filtering viruses, like O2 Safe Air ($25) with 98% filtration efficiency for particles down to 0.3 micron, as confirmed by Nelson labs or Vida — offering very affordable 2—ply cotton masks with carbon filters (sold separately) with 99% filtering efficacy for 0.1 micron particles, according to their website. However, we have not tested these masks for wearability, fit, and comfort, and Vida does not have certificate of testing anywhere on their website. For these reason these masks are not our top recommendations.

Update as of November, 2021:

With mask shortage issues resolved, we now have many more options for efficient, tested, and affordable masks that are available for purchase almost everywhere, compared to early 2020. Hence, we updated our list with additional recommended masks. Our recommendation about N95 respirators is still the same, that they should be reserved for healthcare setting and those at high—risk jobs. Keep in mind that in the last year or so there have been a lot of fake, counterfeit masks sold at different websites, including Amazon. In addition, some masks marked as KN95 and N95 had much lower filtering efficacy when independently tested by CDC (some as low as 5%?!). Please take a look at this CDC summary of counterfeit mask brands. Hence, we only recommend purchasing masks directly from a company or from a certified reseller, like the ones listed below. Also you should only buy KN95 masks that have GB2626-2006 or GB2626-2019 printed on the mask. Both of these standards require filtering efficacy of >95% and masks meeting either standard are recognized by OSHA as providing "similar filtration as NIOSH-certified equipment."

  • Powecom KN95 — This KN95 mask is the most comfortable, easy to breathe, and affordable mask I have tried. It is independently tested by NPPTL, CDC, and Consumer Lab and has shown to have filtration efficiency of >95% for particles larger than 0.3 microns, which conforms to the NIOSH N95 criteria for filtering efficiency. The mask has adjustable nose piece and fits extremely well around the face. It comes in white, black, and hot pink and costs $1.2 — $1.6 per mask. Powecom also offers child—size mask, which is excellent option for school thanks to low cost, comfort, and ease of breathing. is the certified seller of these masks in the US.

Powecom KN95 mask for covid
Powecom KN95 mask
  • Slip Mask — This mask has not been independently tested for filtration efficacy, so it is recommended with caution. It is suitable for those looking for natural materials or concerned about inhalation of organophosphate esters, used to treat some K95 and KN95 masks. It can also be a good choice for low risk activities and low community spread, as well as those special occasions when you want a really fancy mask (I wore it to Paris Hilton's wedding, for example). The mask is made from 3 layers, which fits CDC recommendation for cloth masks. The layers are silk — cotton — silk, a combination of materials shown in an independent study to provide the highest filtration efficacy for cloth masks of >90% for particles larger than 0.3 microns, which is remarkable. Silk is also very comfortable to wear, it cools the skin especially in the summer, and wicks away moisture. This mask does not cling to the face, it has adjustable nose piece for better fit, and it looks very luxurious. It is reusable and can be hand washed with warm water and soap.

Slip mask for covid
Slip mask

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