[lloydarmbrust]

Not exactly.. it really depends on the situation.

For example an ASTM 2 or 3 surgical mask fabric has a filtration of 98%+

On my face I have a leakage of about 21% or PFE of 79% when worn normally.

With an ear saver, it jumps to 91%.

With a mask brace, it jumps to 98%.

So it really is about the fit.

If I put leakage % it would vary from person to person and many people would be mislead by this.

[divbzero]

> On my face I have a leakage of about 21% or PFE of 79% when worn normally.

> With an ear saver, it jumps to 91%.

> With a mask brace, it jumps to 98%.

I had no idea it could vary so much for surgical masks. I’d be curious what range of leakage people could typically expect for other designs such boat-shaped KF94 or flat-fold KN95 masks.

Fit seems important enough to deserve a mention in the intro paragraph at the top of the home page. A more detailed explanation, including the example you gave of how much it can vary for even one person, could go in the “Click here” link to the full testing methodology.

Thank you for doing this, by the way, rare to see a manufacturer test so far beyond their own masks. It clearly takes resources to do this and is a great service to all of us who have been relying on guesswork.

[lloydarmbrust]

Okay I put a disclaimer right on the front and we are typing up an explanation right now. Thank you for this feedback!

https://www.armbrustusa.com/pages/mask-testing

[bagacrap]

thanks! all the notes about fit will be very helpful, including how to use the extra accessories you mentioned above.

For example I found this study on beard length which made me reconfigure my facial hair: https://www.nature.com/articles/s41370-021-00337-1

The charts in that paper also make it seem that n95 *typically* has a much better seal on the face which is worth noting.

I also wonder if the breathability you're measuring affects filtration, given imperfect fit. I would imagine that worse breathability would cause more air to flow around the mask rather than through it.

[wrycoder]

How did you determine those percentages?

[lloydarmbrust]

Using the industry standard TSI PORTACOUNT® RESPIRATOR FIT TESTER 8048

It measures the air outside the mask verses inside the mask.

https://tsi.com/products/respirator-fit-testers/portacount-r...

[creato]

Do you have the same measurement for you for an N95 with the typical elastic straps that you can share?

[lloydarmbrust]

Yes but it differs from model to model.

I get as low as 80% and as high as 99% on my face.

Fit is a big deal because it's personal and hard to communicate. I think it was Amazon that found when scanning their workforce that they discovered 29 different face shapes!