The case against masks is quite trivial and generalizable across most industries.
Today, a teacher now has two realistic options:
a) self-isolate indefinitely, either teaching remotely or quitting their job
b) contract coronavirus at some point
Given that, masks are an irrelevance. A teacher who is clinically vulnerable and unwilling to roll the dice is left only with the option to quit their job, regardless of whether masks are used, or windows are left open, or whatever else.
Coronavirus is too contagious for any sort of avoidance strategy to actually work. It's not like, say, cooking chicken, in which you can basically solve food poisoning.
Today, a teacher now has two realistic options:
a) self-isolate indefinitely, either teaching remotely or quitting their job
b) contract coronavirus at some point
Given that, masks are an irrelevance. A teacher who is clinically vulnerable and unwilling to roll the dice is left only with the option to quit their job, regardless of whether masks are used, or windows are left open, or whatever else.
Coronavirus is too contagious for any sort of avoidance strategy to actually work. It's not like, say, cooking chicken, in which you can basically solve food poisoning.