The important parts:
> cotton masks, surgical masks, and N95 masks all have a protective effect with respect to the transmission of infective droplets/aerosols of SARS-CoV-2 and that the protective efficiency was higher when masks were worn by a virus spreader. Importantly, medical masks (surgical masks and even N95 masks) were not able to completely block the transmission of virus droplets/aerosols even when completely sealed.
> To allow quantification, we conducted our studies by using a relatively high dose of virus, and under these conditions, it is possible that the protective capacity of the masks was exceeded.
And this:
> In our experiments, the virus was suspended in culture supernatant without fetal calf serum or was diluted with phosphate-buffered saline. Further detailed analysis will be required to reveal the precise relationship between the protective efficiency of masks and the components of viral droplets/aerosols.
I wonder if they are planning experiments with artificial saliva, like those people which tested the stability of the virus under sunlight did.