02/06/2021
~ MASK FIBERS AND TINY PARTICLES ~
tl;dr: please wear a mask. 😷 💜
This is an SEM image of a HEPA filter, the gold standard in air purification and respiratory protection. Below the image, to-scale visual representations of the relative sizes of respiratory aerosols and a SARS-CoV-2 virion (i.e., virus particle). The focal plane in this image is extremely shallow at 87 µm—it would take many images like this to cover the entire thickness of a filter.
Note that the fibers are much farther apart than the diameters of most of the exhaled particles, yet, contrary to a common maskconception, the filter is still able to capture the vast majority of the particles. Note also that the fiber arrangement is random. This is part of the design. The goal is to disrupt the air current as much as possible as it passes through the filter material, forcing particles to take long and circuitous routes through the fiber matrix, which greatly increases the chances a particle will be captured by a fiber.
Contrast this with the ordered pattern of mesh filters and sieves, which capture particle by having pores smaller than the target particles. Masks, respirators, and air filters do not function this way. Instead, they capture particles via inertial impaction, interception, and diffusion. Furthermore, virions do not exist in nature as free-floating particles. Rather, they hitch rides on respiratory aerosols and droplets many times larger than an individual virion, making it much easier to prevent their spread through the use of masks and respirators.
So, cover your beautiful faces with a mask to keep each other safe and healthy!
💜
~K