Figure 4.

Mask requirements and usage by countries, obtained from Mask4All, latest update on 24 June 2021 [80]. Green indicates countries where they had countrywide mandatory mask use laws in place or had reached universal usage (mask use by >80% of the population) through recommendations from the government. Yellow indicates countries where mask use was mandated by law in parts of the country and recommended by government in other parts. Red indicates countries where no mask laws and no recommendations were given by the government.