FIGURE 4.

(A) Mask volume and operating temperature that is required to achieve 3‐log reduction in SARS‐CoV‐2 concentration through a heated mask. Results are plotted as a function of a partition coefficient, K _p, which captures impedance of virus in the porous mask mesh, with K _p = 0 indicating that virus is transported with the same velocity as air in the mask, while  K _p ≫ 1 indicates substantial slowing of viral particles relative to air. A 3‐log reduction in inhaled virus can be achieved in masks with volumes less than 0.4 L at temperatures below 100°C if there is slight viral impedance in the mask ( K _p > 1). (B) Mask volume and operating temperature that is required to achieve 6‐log reduction, or sterilization, of SARS‐CoV‐2 concentration through a heated mask. A 6‐log reduction in inhaled virus can be achieved in masks with volumes less than 0.4 L at temperatures below 100°C with moderate viral impedance in the mask ( K _p > 2) [Color figure can be viewed at wileyonlinelibrary.com]