Since March 2020, the world has faced a situation unbelieveable for these times of technological advances.
The situation is a pandemic caused by the SARS-CoV-2 virus or type 2 severe acute respiratory syndrome coronavirus. In the news, it is referred as Covid-19 that means coronavirus of 2019. Yes, the virus appeared in the city of Wuhan, China at the end of 2019 and spreaded around the world since the spring of 2020.
The use of covermasks has been popularized as a shield to minimize the risk of infection by this virus.
But, why not all of the covermasks are effective and what is the reason of the effectiveness for the god ones? Well, we can use the metric scales of the Decimal System of Units for explaining this situation.
