Either they are effective or they are not.
If they are not, then why am I required to wear one for every client I see (NHS mental health).
If they are, then why am I not meant to wear one round tesco as apparantly they are pointless and don't help(?)
What is the difference between coming into contact with clients who may/may not have cv-19, and Jo-blogs who may/may not have cv-19.
I strongly suspect the advice is/should be, that everyone should wear a mask for things like going to tesco. But, the government is having to fudge this as if we did all wear one, there wouldn't be enough for NHS staff.