This is first time to discovered a signage like this.Is there something lke that in your country?
So I 'm sure that it is not polite action.
If there are 3 people here, we can’t know the person who farted(had bad powder).
We are wandering about it. But of course we can’t ask about that.
If I come across a situation, I’ll tell them to leave and fart eleswhere.
