Masks vs Respirators
Before we go any further, let’s just clarify a technical difference between a “mask” and a “respirator”. In day to day language, we often say mask, when referring to what are technically called respirators.- Masks are loose fitting, covering the nose and mouth
- Designed for one way protection, to capture bodily fluid leaving the wearer
- Example – worn during surgery to prevent coughing, sneezing, etc on the vulnerable patient
- Contrary to belief, masks are NOT designed to protect the wearer
- The vast majority of masks do not have a safety rating assigned to them (e.g. NIOSH or EN)
- Respirators are tight fitting masks, designed to create a facial seal
- Non-valved respirators provide good two way protection, by filtering both inflow and outflow of air
- These are designed protect the wearer (when worn properly), up to the safety rating of the mask
- Available as disposable, half face or full face
Respirator Standards
Respirator Standards Whilst surgical style masks are not redundant by any means (discussed more below), they aren’t designed to protect the wearer, whilst respirators are. The US Center for Disease Control (CDC) cites the N95 respirator standard as part of the advised protective equipment in their Covid-19 FAQ and their SARS guidance (SARS being a similar type of Corona virus). Which suggests that an N95 or better respirator is acceptable. N95 vs FFP3 & FFP2 The most commonly discussed respirator type is N95. This is an American standard managed by NIOSH – part of the Center for Disease Control (CDC). Europe uses two different standards. The “filtering face piece” score (FFP) comes from EN standard 149:2001. Then EN 143 standard covers P1/P2/P3 ratings. Both standards are maintained by CEN (European Committee for Standardization). Let’s see how all the different standards compare:Respirator Standard | Filter Capacity (removes x% of of all particles that are 0.3 microns in diameter or larger) |
FFP1 & P1 | At least 80% |
FFP2 & P2 | At least 94% |
N95 | At least 95% |
N99 & FFP3 | At least 99% |
P3 | At least 99.95% |
N100 | At least 99.97% |
KN95 vs N95
Yes. N95 has the same specification as the Chinese KN95. See 3M document (link) – to quote “it is reasonable to consider China KN95, AS/NZ P2, Korea 1st Class, and Japan DS FFRs as equivalent to US NIOSH N95 and European FFP2 respirators” Things to watch out for:- No guarantee that all KN95 respirators meet the KN95 standard – watch out for scams
- Also look out for – good seal around face / some padding for comfort / tie around face straps with adequate strength and tension
Are N95/N100 actually better than FFP2/P3?
Not neccessarily, it’s important to note that these standards only specify the minimum % of particles that the respirator filters. For example, if a mask is FFP2 rated, it will filter at least 94% of particles that are 0.3 microns in diameter or larger. But in practice it will filter somewhere between 94% and 99%. The precise figure will often be quoted by the manufacturer in the product description. A good example is the GVS Elipse respirator, which in the USA (link) is rated at P100 (99.7%), and in Europe (link) is rated at P3 (99.95%). In practice it’s likely to have the same filtering capacity in both regions.Valve vs Non-Valved Respirators
How big is the Coronavirus, and can respirators filter it?
TL;DR – yes, respirators with high efficiency at 0.3 micron particle size (N95/FFP2 or better) can in theory filter particles down to the size of the coronavirus (which is around 0.1 microns). What that doesn’t tell us is how much protection respirators will provide against coronavirus when in use – we will need to wait for future studies to confirm. Read on to learn more… A recent paper shows that the coronavirus ranges from between 0.06 and 0.14 microns in size. Note that the paper refers to the coronavirus particle as 2019-nCoV, which was it’s old name. The virus is currently called SARS-CoV-2, and the illness it presents in people is called Covid-19.- This article by 3M discusses research showing that all 6 of the N95 respirators they tested can efficiently filter lower than 0.1 micron size with approximately 94% efficiency or higher. The graph below is from that article, and illustrates this:
- Additionally, smartfilters.com has a great article on this subject, citing research showing that the respirators tested could filter down to 0.007 microns (much smaller than Covid-19). For example, the 3M 8812 respirator (FFP1 rated) was able to filter 96.6% of particles 0.007 microns or larger. Suggesting FFP2 or FFP3 would achieve even greater filtration.
Image of coronavirus vs other particles – from smartairfilters.com
Risks With Using Respirators
There are a number of possible risks with respirators that it’s worth being aware of, so that you can avoid making them.- Not fitting and wearing respirators correctly– A respirator can’t fully protect you if it doesn’t fit your face. See OSHA; guidance on fit testing and fit checking for more info.
- Touching the front of the respirator(which catches viruses etc) and then transferring that to other objects, which could eventually lead back to your mouth and nose.
- Taking unnecessary exposure risks because you’re wearing a respirator. Don’t let it give you false confidence. The safest thing is maintaining social distance.
Reliable Brands?
For those outside the UK or USA, look for brands that carry ratings appropriate to your country. For example, China has a KN95 standard that uses China GB2626-2006 standard and is almost identical to N95 standard. See this 3M PDF for more details on other standards (including Korea and Japan).Respirator Re-Use – How to sanitize them safely?
Research from SmartAirFilters (link) showed that after 11 days of heavy use in polluted Beijing, their respirator had only lost 1.4% of filtering capacity. So we know that disposable respirators can continue to function for more than 1 day/1 use – fortunately!Better Decontamination Options | Worse Decontamination Options |
✅ Time & Heat – Early research suggests that a combination of time and heat will inactivate the virus. At room temperature (~20C/68F) this may require more than 3 days, but at higher temperatures, the duration may be shorter* | ❌ Washing with soap – Whilst washing respirators can remove SARS-CoV-2, it reduces the filtering capacity significantly* |
✅ Oven Heat – 70C (148F) heat for between 5 and 30 minutes may inactivate the virus* | ❌ Alcohol – Whilst cleaning with 70%+ alcohol can inactivate SARS-CoV-2, it reduces the filtering capacity significantly* |
✅ Steam – hot water vapor from boiling water for 10 mins was able to kill a substitute for SARS-CoV-2* | ❌ Overnight Storage – Two studies suggest Covid-19 can survive for at least 3 days (72 hours) on plastic. Indicating that overnight storage at room temperature is not sufficient for decontamination.* |
✅ UV-C Light – 67 J/m2 of UV-C will inactivate SARS-CoV-2 with low levels of damage to the respirator* | ❌ Bleach Immersion – Whilst bleach can be an effective way to inactivate SARS-CoV-2, immersing respirators in bleach containing solutions can degrade filtration efficiency.* |
Surgical Masks
Surgical masks are generally speaking a 3-ply (three layer) design, with 2 sheets of “non-woven” fabric sandwiching a “melt-blown” layer in the middle. It’s the melt-blown layer that provides the filtering capability. A melt-blown material is also used in respirators, and thus you can imagine it’s more expensive and hard to come by recently, due to demand.Diagram of melt-blown machinery (left) comes from Erdem Ramazan’s book, and the image of melt-blowing in progress (right) comes from 4FFF on wikipedia
Not all melt blown fabric has the same filtering capability, some are better than others. Unfortunately, we can’t test the filtering capability of the melt-blown layer without specialized knowledge and equipment. What we can do, however, is at least check that the melt-blown layer is present. Below I show an example of a surgical mask (left) that came without the melt-blown layer. You can imagine that, given the extra cost and current scarcity of melt-blown fabrics, manufacturers might cut corners with this layer, so it’s worth keeping an eye on.Can Surgical Masks Filter the Coronavirus?
RESULTS 1 Among 2862 randomized participants (mean[SD]age, 43[11.5]years;2369[82.8%])women), 2371 completed the study and accounted for 5180 HCP-seasons. There were 207 laboritory-confirmed influenza infection events (8.2% of HCP-seasons0 in the N95 respirator group and 193 (7.2% of HCP-seasons) in the medical mask group (difference, 1.0%,[95% CI,-0.5% to 2.5%];p=.1809adjusted odds ratio [OR], 1.18 [95% CI, 0.95-1.45]) There were 1556acute respitory illness events in the respirator group vs 1711 in the mask group. CONCLUSIONS AND RELEVANCE Among outpatient health care personnel. N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.In the next study, Canadian nurses were split into 2 groups, those wearing N95 masks and those wearing surgical masks. There were 50 cases of influenza in the surgical mask group, compared to 48 in the N95 respirator group2. Again, no significant difference.
RESULTS 2 Between September 23, 2008, and December 8, 2008, 478 nurses were assessed for eligibility and 446 nurses were enrolled and randomly assigned the intervention; 225 were allocated to receive surgical masks and 221 to N95 repirators. Influenza infection occured in 50 nurses (23.6%) in the surgical mask group and in 48 (22.9%) in the N95 respirator group (absolute risk difference, -0.73%; 95% CI, -8.8% to 7.3%; p=.86) the lower confidence limit being inside the noninferiority limit of -9%. CONCLUSION Among nurses in Ontario teritory care hospitals, use of a surgica mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed infuenza.So where does this leave us? Those 2 studies suggest that surgical masks are approximately comparable to N95 masks when it comes to preventing influenza illness in close contact clinical settings. What this doesn’t tell us, is whether they’re better than wearing nothing on our faces. To find that out, we need a study that has a control group that doesn’t use any facial protection. Due to ethical considerations, those studies aren’t abundant, but we do have at least one. In this Australian study, they looked at 286 adults in 143 households who had children with influenza-like illness3. For clarity, influenza-like illness is not the same as laboratory-confirmed influenza. It’s diagnosed by symptoms like fever, dry cough and feeling sick, which could mean influenza but could also be caused by the common cold or other viruses. They found that adults who wore masks in the home were 4 times less likely than non-wearers to be infected by children in the household with a respiratory infection. There is a nice analysis of the study here by Imperial College London.
- Wearing a surgical mask or N95 (FFP2) respirator was better (in the study) at protecting against influenza-like illnesses than wearing nothing at all
- Whilst we can anticipate surgical masks to be inferior to respirators, the studies above suggest they are not as inferior as one might assume. For example, the first two studies didn’t find a significant difference between surgical masks and N95 respirators when protecting wearers against influenza.
- Important to note that we’ve used influenza protection as a proxy for SARS-CoV-2 (coronavirus). This is done because SARS-CoV-2 is new and there are no comparable studies on it. But of course, the drawback is that it still leaves a lot of uncertainty, as SARS-CoV-2 may act quite differently in terms of transmission.
What are respirators protecting us against?
Droplets A primary reason for wearing a respirator is to protect from droplets. For example, if a sick person coughs or sneezes when in close proximity to us, the respirator forms a barrier to prevent their bodily fluids from reaching our face. Droplets are generally large, and gravity drags them down to land on objects, rather than staying in the air. So they don’t travel very long distances. There is however research into microdroplets, which get ejected even during talking. This Vimeo video made by Japanese researchers captures microdroplets on video using high-speed cameras. We know large droplets play a role in transmission, but it’s not yet clear what role microdroplets play.Is Eye Protection Necessary?
Related Questions…
What can you do to reduce risk?
Social Distancing Viruses like the flu and novel coronavirus are spread by people who have the virus coming in to contact with people who are not infected. The more you come in to contact with infected people, the more likely you are to catch the infection. Social distancing, according to Wikipedia, is infection control actions that are taken by public health officials to stop or slow down the spread of a highly contagious disease. We are seeing this in action already in countries such as China, South Korea, and Italy. In addition to social distancing measures taken by governments, we can ourselves choose to reduce physical exposure to potentially sick people, for example:- Exploring the option to work from home if your job allows for it.
- Avoiding large public gatherings such as sporting events or situations where you may come in to contact with crowds of people (such as shopping malls, gyms or cinemas)
- Interacting with people over the phone/video calls, instead of in person.
- The CDC recommend regular hand washing with soap and water for at least 20 seconds.
- Prioritize washing prior to eating and after being out.
- Regular hand washing dries the hands, which at an extreme, may make them vulnerable to infection. To mitigate this, regularly use a glycerin based moisturizer with pump or squeeze mechanism. Those that you scoop are less hygienic.
- A study showed that we touch our face on average 15x per hour. That behaviour may be difficult to change, but if we keep our hands clean, it’s less detrimental.
- Computer keyboard and mouse
- House and car keys
- Re-usable water bottles
- Car steering wheel
- Clothing pockets
- Door handles
- Vitamin D plays a key role in immune function
- Being deficient in vitamin D can make you more susceptible to infection
- Vitamin D supplementation protects against acute-respiratory tract infections
- Whilst noting that none of this relates specifically to the coronavirus, but is about general healthy immune function
CONCLUSIONS Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit.From a British Medical Journal meta-analysis, covering 25 randomized controlled trials (11,321 participants).
ABSTRACT It is now clear that vitamin D has important roles in addition to its classic effects on calcium and bone homeostasis. As the vitamin D receptor is expressed on immune cells (B cells, T cells, and antigen-presenting cells), and these immunologic cells are all capable of synthesizing the active citamin D metabolite, vitamin D has the capability of acting in an autocrine manner in local immunologic milieu.Vitamin D can modulate the innate and adaptive immune responses. Deficiency in vitamin D is associated with increased autoimmunity and an increased susceptibility to infection. As immune cells in autoimmune diseases are responsive.From a British Medical Journal article on Vitamin D and the immune system We can get vitamin D from our diet (small amounts) and from sun exposure. If you’re not getting much sun, it can be difficult to get adequate amounts of vitamin D from the diet alone. What is an adequate amount of vitamin D? The National Institutes of Health (NIH) suggest getting 600iu (15mcg) from all sources, per day, for adults. Similarly the National Institute for Health and Care Excellence (NICE) suggest a supplement containing 400iu (10 micrograms) taken daily. Dr John Campbell has a great video on vitamin D and the immune system . He cites the NICE guidelines of supplementing 400iu per day, and says he personally takes a vitamin D supplement containing 1,000iu daily. When looking for a supplement, there is evidence to suggest (link) that vitamin D3 raises levels of vitamin D with 1.7x greater efficiency than D2. Examples of NSF certified manufacturers selling vitamin D3 are Life Exension – 1,000iu, Thorne Research – 1,000iu and Pure Encapsulations – 1,000iu. Roundup Hopefully if you’ve stumbled across this article, and you were confused about the difference between N95, KN95 and FFP2/FFP3 masks, this has cleared things up for you. For Spanish speaking friends who might find this article useful, it’s translated here. If you have any further questions, please leave them below in the comments. See Post Sources Below:
- Summarised from the blog post by fastlifehacks.com https://fastlifehacks.com/n95-vs-ffp/ – John Dotz – April 2020
- N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel – A Randomized Clinical Trial– Lewis J. Radonovich Jr, MD et al. – JAMA – Sept 2019
- Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers – A Randomized Trial– Mark Loeb et al. – JAMA – Nov 2009
- Face Mask Use and Control of Respiratory Virus Transmission in Households– MacIntyre et al. – Emerging Infectious Diseases Journal – Feb 2009
- Sick and tired: does sleep have a vital role in the immune system?– Bryant et al. (2004)
- Exercise and the Immune System– Brolinson (2007)