[Moderator Edit: I'm reopening this question by request from third parties because medical staff around the world are being forced to use masks such as these.]

How does a sanding mask compare with a disposable medical mask? I have some on hand. Would that be a reasonable thing to wear to protect myself and family members (corona virus)? Or would it give even less protection than a bandanna or a disposable medical mask?

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Update: I'm asking about the range of particle and droplet size that the two types of mask keep in/out (according to specs, and disregarding particles that can enter around the edges).

I am not asking whether you think someone should or should not wear a mask.

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  • Your question doesn't provide any specs for this mask, so how can we compare it to a medical N95 mask, which has well defined specifications? The question is salvageable with a bit of research. – Carey Gregory Mar 16 '20 at 15:20
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    The mask in the image shows it's marked as a FFP2 which is a standard. – Graham Chiu Mar 20 '20 at 5:26

Particle Size-Selective Assessment of Protection of European Standard FFP Respirators and Surgical Masks against Particles-Tested with Human Subjects

The tested FFP respirators and SMs in this study were observed to have the worst protection against particles between 0.263 and 0.384 μm. The protection factors of FFP respirators against particles in the size range of 0.093–1.61 μm were not size dependent. The size ranges of viral and bacterial particles fall into this size range, and they are expected to have similar PFs. The FFP respirators provided about 11.5 to 15.9 times better protection than the SMs, suggesting that SMs are not a good substitute for FFP respirators when concerns exist about airborne transmission of bacterial and viral pathogens.


That's a FFP2 in your image and they are saying it's 12-16x better PF (Protection Factor) than a surgical mask (SM)

  • FFP2 are also known as N95 in the US (also FFP3 = N99). If I'm allowed to relate some practical experience here: a good brand P2 mask can be better in practice than a crappy P3 one, at least far as dust is concerned, which probably is a good proxy for other things too. In general, the cheesy ones have problematic side/nose sealing (e.g. too stiff), so they might pass the test on a dummy head, but not do well on a moving person. – Fizz Mar 22 '20 at 9:06
  • Also, in clinical practice (as opposed to laboratory) trials, the difference between SMs and N95 was generally lot harder to show. E.g. ncbi.nlm.nih.gov/pmc/articles/PMC4868605 – Fizz Mar 22 '20 at 9:16
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    I wasn't aware that P2 was a short acronym of the existing acronym FFP2! – Graham Chiu Mar 22 '20 at 10:35
  • And yes there appears to be no practical difference suggesting it's large droplets that are the issues. – Graham Chiu Mar 22 '20 at 10:38
  • "I wasn't aware that P2 was a short acronym of the existing acronym FFP2", P2 is sometimes used e.g. health.nsw.gov.au/environment/factsheets/Pages/face-mask.aspx Fraknly, I don't know if dropping "FF" is inconsequential or not on a strictly standards/technical level. On thing I do know is that masks ending in a "D" (for dolomite test, e.g. FFP3-NR-D) are somewhat harder to clog with dust, but also a bit harder to breathe through to begin with, in my experience. (So the final "D" does make a practical difference) – Fizz Mar 22 '20 at 10:52

For protecting against saw dust (sanding), they work great!

For protecting from biological risks in a medial setting, they're up to half as effective.

Assuming we're discussing the respirator in the photo you uploaded with your question, note that it has a plastic valve in its center. This is an exhilaration valve. The exhilaration valve is a one-way valve that permits air to pass unobstructed out of the respirator. This is great when doing construction work; it makes breathing (out) easier.

However, respirators with exhalation valves necessarily do not filter your exhalation, so they are not very effective at preventing the spread of biological infectious agents, such as the coronavirus. In fact, the CDC recommends that if you only have an N95 mask with an exhalation valve, then you should wear it along with a surgical mask on the outside 1.

One of the biggest issues with the spread of COVID-19 is that many people who contract the virus (and can spread it to others) never experience symptoms (asymptomatic) or they can spread the virus for up to 14-days before they experience symptoms (pre-symptomatic) [2]. Therefore, it's very important that you use a respirator that filters both your inhalations and your exhalations.

That said, any filter is better than no filter.

  • side-note: OP mentioned a bandanna, some less-than-ideal studies showed that bandannas can filter ~20% of particles at 0.3 microns. So a well-fitting surgical mask > sanding mask > bandanna > nothing – Michael Altfield Sep 22 '20 at 10:52

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