It might be that as you exhale more and more viruses get into the mask and while the mask filters, when you let clean air go through the mask filled with viruses that air will partly be filled with viruses, so over the span at of a few minutes you are still putting out 80% or virus particles.
Especially, with clothing masks that are not designed to actually do good filtering.
Mask quite clearly prevent droplets but when it comes to aerosol the case is less well (I have heard the hypothesis is that this is partly the reason why the WHO still hasn’t accepted that COVID-19 transmits via aerosol.
In the thread model of aerosol transmission a bunch of good airfilters might do more then a clothing mask.
It might be that as you exhale more and more viruses get into the mask and while the mask filters, when you let clean air go through the mask filled with viruses that air will partly be filled with viruses, so over the span at of a few minutes you are still putting out 80% or virus particles.
Especially, with clothing masks that are not designed to actually do good filtering.
Mask quite clearly prevent droplets but when it comes to aerosol the case is less well (I have heard the hypothesis is that this is partly the reason why the WHO still hasn’t accepted that COVID-19 transmits via aerosol.
In the thread model of aerosol transmission a bunch of good airfilters might do more then a clothing mask.