My response to "why are you wearing a mask?"

All of this leakage in surgical and fabric masks are why public health officials generally don't believe that wearing a mask prevents anyone from catching a virus that is already floating around in the environment. Airflow follows the path of least resistance, said Rachael Jones, an associate professor of family and preventive medicine at the University of Utah who was not involved in the new research. If viral particles are nearby, they have an easy path around a surgical or fabric mask. And in the case of a fabric mask, wearers may well be wafting in particles small enough to flow right through the fabric.

But what about the other way around? When the wearer of a mask coughs or sneezes, the barrier might be enough to contain a lot of that initial jet of grossness — even if there are gaps in the fabric or around the sides. That's what the new mask studies aimed to address: Whether surgical or fabric masks did a good job of containing viruses.

https://www.livescience.com/are-face-masks-effective-reducing-coronavirus-spread.html