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➡️ The best mask is an N95, but all masks work

➡️ Double masking or overmasking

➡️ FAQs are:

❓ Does it make a difference?

❓ Which mask should go on top, the cloth mask or the medical mask?

❓ What about two cloth masks?

❓ Or two medical masks?

➡️ Answers at updated page:



The most efficient respirator is an N100 or P100 elastomeric, not N95.

Generally, you should not wear anything over a FFP N95 because it can distort the shape of the mask and allow air to leak in around the mask.

If you are in a setting where you need to protect against splashed liquids as well as from airborne particles, then consider wearing a face shield, or wear a medical N95 that is resistant to body fluid splashes.

If you are trying to protect against current variants of the SARS-CoV-2 virus, you should wear an N100 or P100, especially if you are in an enclosed space with someone who is symptomatic, because an N95 may not filter out enough of the virus particles to prevent infection.


Also, if are worried about source control, you can wear a procedure mask or surgical mask over the exhaust valve of your elastomeric (on some models), but make sure it is loose enough so that is doesn't interfere with the seal of the mask. (If you need complete source control, then you'll need a SCBA respirator, and lots of other protocols.)

@Pat I'm not sure why anyone who understands transmission would wear a respirator with an exhaust valve?


>"I'm not sure why anyone who understands transmission would wear a respirator with an exhaust valve?"

- When you properly wear an N100/P100 elastomeric respirator whenever you are in a potentially contaminated environment, your chances of becoming infected approach zero, which means you're not a source, so source control is unnecessary. (In effect, the source control occurs during inhalation.)

- If the valve is properly maintained, it will not allow leakage under negative pressure.

- Source control in the general population is only effective when nearly everyone practices it (and then only partially effective). When half of the people are running around without any mask at all, it becomes pointless.

- An exhaust valve greatly increases comfort, especially when wearing the respirator for long periods.

>"The most efficient respirator is an N100 or P100 elastomeric, not N95."

*Most efficient at a reasonable price. PAPR respirators are more efficient but cost thousands of $.

Hi @Pat, you and I discussed this before. I'm posting about a community setting. Without fit testing, I wouldn't recommend a N100 over an N95.

To be totally literal, the best mask is a powered air-purifying respirator (PAPR) and a hazmat suit. But that isn't a very useful or practical recommendation. Thanks for following and for your comments.


>"Without fit testing, I wouldn't recommend a N100 over an N95."

Many elastomerics have special valves for closing the the inlets during a seal check. If someone knows how to do that (which is very easy to learn), then those respirators can provide a much better seal and more efficiency than an N95 FFP.

>"Thanks for following and for your comments."

Thank you for the discussions...



➡ Physical interventions to interrupt or reduce the spread of respiratory viruses

The pooled results of RCTs did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory viral infection.

Research study:

➡ Respiratory Performance Offered by N95 Respirators and Surgical Masks: Human Subject Evaluation with NaCl Aerosol Representing Bacterial and Viral Particle Size Range

Most of the tested N95 respirators and surgical masks in this study were observed to perform at their worst against particles approximately between 0.04 and 0.2 μm, which includes the sizes of coronavirus and influenza virus.

➡ The Foegen effect
A mechanism by which facemasks contribute to the COVID-19 case fatality rate

This study revealed that wearing facemasks might impose a great risk on individuals, which would not be mitigated by a reduction in the infection rate. The use of facemasks, therefore, might be unfit, if not contraindicated, as an epidemiologic intervention against COVID-19.

Opinion articles:

➡ The Mask Mandates Did Nothing. Will Any Lessons Be Learned?

➡ Does this finally put the mask debate to bed? ‘Gold standard’ analysis of 78 studies and 1million people finds face coverings made ‘little to no difference’ to Covid infection or death rates

➡ Do We Need Mask Mandates?
The science suggests that more states should consider rescinding them.

➡ The Real Science on Masks: They Make No Difference

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