According to Wikipedia, "Each SARS-CoV-2 virion is approximately 50–200 nm (nanometres) in diameter."
According to
https://www.news-medical.net, "researchers have determined the diameter of this virus to range between 60 nanometers (nm) to a maximum diameter of 140 nanometers (nm)."
Now take a cotton mask made from tee shirt material. According to
https://www.mathscinotes.com/2013/12/t-shirt-and-cotton-fiber-math/ it is reasonable to assume that each thread is 0.1203 mm and thread count is about 150 threads per inch (which 5.9 threads per mm). So 0.1203 times 5.9 means that threads make up 0.71 of each mm. Therefore, 0.29 mm is left for total space between the threads. Divide that again by 5.9 threads per mm and we get spacing between each thread of 0.049 mm (millimeters). This equates to 49,000 nanometers.
Whoa. Hold the horses. The mask (that is supposed to stop the covid virus which has a maximum size of 200 nm) has holes in it that are 49,000 nm wide (if evenly spaced, i.e. not stretched)
One does not need to be a rocket scientists to understand this is a serious problem. Of course that may be too logical for people that mainly reside in their protected and safe spaces, totally devoid of reality.