These filters look "not enough" to filter very small particles. There should be more than one layer in them (judged by the pictures/imho). Also, a channel in th

These filters look "not enough" to filter very small particles. There should be more than one layer in them (judged by the pictures/imho). Also, a channel in the middle is needed (the "Dyson principle") for the particles being centrifuged in the center and not being just blown into the air again (just my humble engineer opinion). Also, it needs to be taken into account that the virus filled droplets dry faster, the more dry the air is. But the more dry the air, the more the particles stay in the air. So maybe a good idea would be to prolong the way the air stays within the box and apply some heat or use a UVC lamp inside or something. Otherwise, there is a possibility that the very fine droplets won't stick to the filter but being blown into the air again. - still better than having a droplet-cloud waving through the room -