Colleagues at the University of Bristol and I are working on understanding how face coverings/masks filter our potentially infectious droplets.
As of early December 2020 there is a preprint on medRxiv:
by Joshua F. Robinson, Ioatzin Rios de Anda, Fergus J. Moore, Florence K. A. Gregson, Jonathan P. Reid, Lewis Husain, Richard P. Sear, C. Patrick Royall
An earlier (August 2020) report, more technical and focused on the physics of filtration is on the arXiv:
Efficacy of face coverings in reducing transmission of COVID-19: calculations based on models of droplet capture
Code written by Joshua Robinson (University of Bristol) and I, that was used for the calculations in this work is on Github here.
The pdf of the slides of my talk entitled Some simple physics of corona virus transmission at SOFT MATTER: THE UNSEEN SCIENCE ALL AROUND US is here I cover both simple models of person-to-person transmission of SARS-CoV-2, and of masks/face coverings.