Meetup Organizers, Our Virtual Garden is at Your Disposal

Hi, we might want to try holding the LW-Cologne meetup at the Walled Garden. What should I do?

Hammer and Mask - Wide spread use of reusable particle filtering masks as a SARS-CoV-2 eradication strategy

Well, difficult at the moment. I would try the M3 6000 or 6500 series first since they are available in 3 sizes. But you basically have to shop around until you find something, which is difficult when most shops are sold out.

The Hammer and the Mask - A call to action
The interpretation I have for the mask is that we say y at any distance = mask rating (95 or 99).

This simple conversion does not work, since the drop of particle concentration over a certain distance is not fixed and drop size is not fixed. Under very favorable conditions you may get an infectious dose over 60 feet though that is quite unlikely.

But those filter materials may be something of a bottle neck too (and clearly do compete with providing masks to the medical workers.

That is my point. We should start manufacturing masks and filter material en masse NOW so we can provide everyone with a high quality mask in 2 to 3 months. Noone does this at the moment and what is produced is wasted on crappy one way products even most professionals do not use correctly.

The Hammer and the Mask - A call to action

I think it has more to do with N99 not being available in the filtering facepiece form which are the medical standard with very few exceptions.

The Hammer and the Mask - A call to action

Pretty sure. You should not get your filter wet though since this may allow diffusion across the filter, which is why it is unsafe to wear (N 95 or other) fleece masks for extended periods. Also stuff that is bound in the filter is also attracted via Van-der-Waals forces which are really strong on this scale.

The Hammer and the Mask - A call to action

Yeah, it will be way more than 99% of virus particles since most virus particles are bound in larger droplets where filtration efficiency is much higher than 99 %.

The Hammer and the Mask - A call to action

Adsorption air filters are not sieves or membrane filters, particles are captured by adsorption to the filter medium, not by size exclusion. The pessimum of filtration efficiency is afaik around 1 µm with higher capture efficieny below that due to higher collision probability due to more brownian motion. Not completely sure of the numbers though.

I'd go with P 99 or 100 since they are not that much more expensive / unpleasant to wear and we want to have as little particle leakage as possible since we do not know how much dose reduction is needed to reduce infection probability by one to two orders of magnitude. A hundredfold seems plenty though.

Also note that virus particles do not fly alone since they are allway bound in liquid or whatever remains after the droplet dries. CoV-2 seems to be nonviable when dried though so you need not worry about dry stuff.

The Hammer and the Mask - A call to action

Exactly, though we should aim to change that since protection would be improved while logistic demands would fall.

Also we should try to get governments to stimulate large scale production of such masks. See my original post.

The Hammer and the Mask - A call to action

This highly depends on mask quality and fit. A well fiting high quality oneshould be about as comfortable as a cloth mask.

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