[hirundo]

> Homemade masks will probably only reach 70% or maybe as low as 50%. You aren't invulnerable, you just have a layer of protection on.

This protection is more than the numbers may seem. See this essay on the benefits of contracting a disease in a smaller dose:

http://www.overcomingbias.com/2020/03/variolation-may-cut-co...

> The most directly relevant data is on SARS and measles, where natural differences in doses were associated with factors of 3 and 14 in death rates, and in smallpox, where in the 1700s low “variolation” doses given on purpose cut death rates by a factor of 10 to 30.

If you can cut the dose by 70%, it gives your immune system more time to ramp up ahead of the virus, which often translates into a more controlled infection with lower level symptoms, if any.