In Thailand, a nurse got infected from the SARS-2 virus in an air-conditioned hospital just because she didn’t wear a mask when dealing with a Chinese COVID-19 patient whereas all the other hospital staff wore masks and didn’t have an infection. Then the neuro professor said that a mask is important to prevent the virus. Unfortunately a week later, there was a severe shortage of the mask in this country. A surgical doctor showed his cloth-made mask full of blood just due to the lack of a real surgical mask.
So the truth is that, if you live in a temperate or air-conditioned zone, a mask can help. But if you live in a tropical country like Thailand or Cambodia where the UV index is very strong and the weather is really hot and humid, a mask is not needed because there is a zero chance of the infection in the outdoor area (I haven’t seen one got infected from the outdoor). The US health officials said so to prevent the shortage.
