Particulate matter at .3 microns is the most difficult to capture. The COVID-19 virus, at roughly .01 microns, is easier to capture due to electrostatic charge or Browning Diffusion (see first graphic above) than the larger particle. Air filtration (such as N95 and N99) is measured against the percentage to capture .3 microns. For instance, an N95 face mask is 95% effective in capturing .3 microns. Capturing this exact particle size is the gold standard of mask filtration. Larger than .3 and smaller than .3 microns are less worrisome as there is an even higher capacity to capture those sized microns (including a virus at .1 microns). The main benefit of electrospun nano-fiber filtration is the high efficiency of filtration with low pressure drop (breathing resistance). An effective product, comfortable to wear.