A KEY ARGUMENT FOR USING HOMEMADE MASKS: Homemade masks are partly effective in individual protection, but they are essential for slowing the spread of the virus in the population. The main outcome of our studies was that they stop around 95-100% of viruses that people emitting by your breath, sneezing, and coughing. People are the most contagious first days without symptoms, that’s why we need masks for all. We have successfully tested the hypothesis at two main technical universities and it is highly recommended by a team of experts COVID CZECH under the coordination of the president of Czech Technical University in Prague. The team consists of a virologist, epidemiologist, doctors with specialization in population protection, chemists, and physicist with specialization if filtration. This group is an advisory expert group for the Czech government in Prague. Now it is obligatory to wear masks in the whole country. Please share and help to spread the key message that can save lives and slow the pandemic. #Masks4All: “I protect you, you protect me.”