Shortly after the release of my article a paper appeared in Nature’s Scientific Reports that investigated the suitability of various types of masks (N95, surgical, cloth, etc) to compare their efficacy in decreasing particle expulsion (source control). This is one of the better of the “pro-mask” type articles in that they are completely open and honest about the limitations of their studies as well as raising a very interesting hypothesis that if true, could very well mean masks are making the spread worse.
The idea is this: you breath out and the masks captures the particles. Ok. Where do they go? They don’t simply vanish into another universe. If they are adhered to droplets and aerosols (water) then once that material builds up on the mask interior further breathing will actually re-aersolize it through the mask spraying it out like a spray can. This would have the effect of creating a much broader and more disperse ejection of material given that it is now concentrated in one spot. Likewise, even if the water particles evaporate leaving the viral particles behind – they still exist – on the mask. They are now attached to the fibers etc of the mask. These are no irreversible chemical bonds, they are loose electrostatic interactions. This is important because this study showed that cloth masks actually produced more particles than no mask at all. The reason for this being that breathing through it cause mask material itself to become dislodged and break free. So if a virus can attach to these then the virus will be hitching a ride on them.
This casts serious doubt on the mitigation effects of masks insofar as it demonstrates the very real possibility that at best they are doing nothing whatsoever and at worst they could be amplifying the spread. The only way to avoid this scenario would be to use N95 or surgical masks and change them out for new ones over the course of a few minutes. We know this is not happening nor is it practical in an real sense to expect that. Therefore the best approach is to only mask the vulnerable with suitable masks and use such masking as a signal to others to maintain a wide berth and take other protective measures. If every tree is marked then which tree has the pot of gold?