jimharri
Moderator
It's a popular expression (not that popular though, apparently, seeing as you presumably haven't heard it). When someone is moved to tears, but they want to keep up a steely persona, they claim that the water in their eyes is caused by dust, or chopping onions, or whatever. They don't want to admit to shedding tears to something like that poor family's plight. I apologise if you think my post was in any way a slight on those people.