  Face masks are used to trap particles (or fluid drops) in a porous material
(filter) in order to avoid or reduce the transfer of particles between the
human lungs (or mouth and nose) and the external environment. The air exchange
between the lungs and the environment is assumed to occur through the facemask
filter. However, if the resistance to air flow through the filter is high some
air (and accompanied particles) will leak through the filter-skin interface. In
this paper I will present a model study of the side-leakage problem.
