Not Hi-Fi -- COVID-19 FYI
Posted: April 11th, 2020, 12:21 pm
Face masks are in great demand and essentially the lead time for stocks was (and is) anywhere from 4 to 6 weeks.
Some of you have probably made your own. If you are looking for self-protection then think again. Here are the numbers:
1 micron = .00004 inch
Diameter of hair = about 75 microns
Red blood cell = about 5 microns
Dust particles = about 2 to 10 microns
Bacteria = about .2 to 3 microns
CORONA-19 = The average diameter of the virus particle is around .12 microns. The diameter of the envelope is .08 μm and the spikes are about .02 microns long.
The medical grade N95 face mask is rated to block at least 95 percent of very small (0.3 micron) test particles.
Masks typically used in dental settings collected particles with significantly lower efficiency than those typically used in hospital settings. All subjects failed the unassisted qualitative fit test on the first exercise (normal breathing).
Eighteen subjects failed the assisted qualitative fit tests; 60% failed on the first exercise. Quantitative fit factors ranged from 2.5 microns to 9.6 microns.
To add insult to injury a 2008 study funded by the Netherlands Ministry of Health, Welfare, and Sports found that a homemade mask, in this case made from a tea towel, was about half as effective as a surgical mask in protecting the wearer from particles in the outside environment.
Some of you have probably made your own. If you are looking for self-protection then think again. Here are the numbers:
1 micron = .00004 inch
Diameter of hair = about 75 microns
Red blood cell = about 5 microns
Dust particles = about 2 to 10 microns
Bacteria = about .2 to 3 microns
CORONA-19 = The average diameter of the virus particle is around .12 microns. The diameter of the envelope is .08 μm and the spikes are about .02 microns long.
The medical grade N95 face mask is rated to block at least 95 percent of very small (0.3 micron) test particles.
Masks typically used in dental settings collected particles with significantly lower efficiency than those typically used in hospital settings. All subjects failed the unassisted qualitative fit test on the first exercise (normal breathing).
Eighteen subjects failed the assisted qualitative fit tests; 60% failed on the first exercise. Quantitative fit factors ranged from 2.5 microns to 9.6 microns.
To add insult to injury a 2008 study funded by the Netherlands Ministry of Health, Welfare, and Sports found that a homemade mask, in this case made from a tea towel, was about half as effective as a surgical mask in protecting the wearer from particles in the outside environment.
