by K2! » Tue May 05, 2020 8:42 am
In case you were wondering...
Particle respirators trap particles by 2 means; first is how tightly the material is woven, which regulates the size of openings for air to pass through. Second is a static electric charge. This static electric charge is literally woven in during manufacturing.
The ratings on these masks have a letter (N, R, or P) and a number. The letter rates the masks resistance to solid and liquid airborne oil particles. Oil may reduce or dissipate the static charge.
N masks are not resistant to oil.
R masks are resistant to oil but will wear out or become clogged by oil particles and should not be worn more than 8 hours in the presence of oil in the air.
P masks are considered oil proof but will degrade over time. Duration should be checked with the manufacturer for a specific mask.
The most common numbers associated with these masks are 95, 99, and 100. This refers to the percentage of particles 0.3 microns or larger filtered by the mask. Therefore 95 is 95% and 99 is 99%. 100 is considered 99.7%.
Some masks have a little plastic attachment on them. This is a one way valve that allows exhalations to be expelled from behind the mask with less pressure than being pushed through the filter portion of the mask. These valves do not affect the filtering capabilities of the mask.
Coronavirus particles are spheres with diameters of approximately 0.125 microns. The smallest particles are about 0.06 microns, and the largest are about 0.14 microns.