Active Shooter Situations

 If an active shooter thinks many people will be carrying guns, he will not carry out his bad act. Just like

 soldiers do not shoot up each other in armed stations,  these situations usually occur in places where the

 shooter is pretty sure there is not opposing armed person.

COVID-19 MASKS

The  n-95 masks do not need to be doubled because they were built to restrict viruses.

The home-made and other surgical masks may be doubled because they were not built for viruses.