[AR] Re: ... Coronavirus
- From: Norman Yarvin <yarvin@xxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Sun, 22 Mar 2020 20:51:37 -0400
On Sun, Mar 22, 2020 at 02:32:33PM -0600, William Claybaugh wrote:
Please correct me if I’ve got this wrong but it has previously been my
understanding that only a Level 3 or better facility has in place filters
capable of capturing virus particles. This based on a visit to a Level 4
facility.
There are all kinds of levels of certainty about filtration. For
"absolutely no virus will get past the filter, ever", that might well
be correct. The N95 masks which are widely recommended and which have
now been sold out and/or overpriced for weeks take their name from
stopping >95% of some specified class of particles. But do you really
want to let the other 5% through? Indeed, there are also N99 and N100
filters, as well as P99 and P100 (the P meaning oil resistant, so you
can spray paint with them; oil resistance isn't useful here but
doesn't hurt). In either case the "100" is not literally 100%, but
something like 99.95%. That's a lot better than 95%, but still not an
ironclad guarantee.
The focus on N95 might be as the best thing available as disposable
masks. I'm not sure if higher-rated disposable masks exist, but even
if you did have a N100 disposable mask, enough air would leak around
the edges to render the "100" meaningless. Usually the higher-rated
filters are fitted to reusable face masks, which have a rubber seal
that is reasonably airtight (with luck, and if put on correctly). Not
that even that seal would have a shadow of a chance of passing a
helium leak test, of course.
Amusingly, the level of concentration on "N95" has been such that for
weeks, although the N95s were all sold out, you could still get a much
superior reusable mask and filters at the normal price of $40 or so
(and perhaps still can, though I see some are sold out).
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