The coronavirus pandemic demonstrated the problem of a total shortage of certified protective equipment and raised the question of their adequate replacement. In fact, from a practical point of view, providing an entire population with medical or industrial-grade protective masks is simply ineffective. They must not only be produced to strict standards, but also educate the public to use them correctly, otherwise they will be useless.
As a consequence, the focus has shifted from medical masks and industrial respirators to simple, improvised masks that anyone can make themselves. But how do you make them effective against viruses?
To begin with, the dimensions of the coronavirus are about 0.08 micrometers, and the distance between the threads in a rag mask is about 1000 times larger (from 0.1 to 1 mm). Therefore, "efficiency" in this case does not mean at all the ability to capture viral particles. In fact, efficiency in this matter means being able to shorten the distance your breath can travel from your body. If you just want to protect yourself from the virus, you still need certified protective equipment of a class not lower than FFP2 (often called N95 masks). But the massive purchase of such masks creates a shortage of them for those who really need them - doctors and rescuers. Therefore, the usual improvised mask is still the best solution.
To see how far a particular mask allows your breath to travel, try a simple test - try to blow out a candle in front of your face. First, learn the distance and expiratory force required for this, and then move on to testing different materials and - more importantly - the number of layers needed. The mask, which makes the most effort to blow out the candle, will make it as difficult as possible for the viral particles to move directly into the face of your interlocutor. Without much more sophisticated equipment, more reliable tests will no longer be possible.