Green moss on maple

I have several sugar maple trees that have a green thin layer of moss, what would be safe to get rid of this? Its only on the trunk and goes up from the base a few feet. Even the side with late afternoon sun has stayed throughout the year. I have kids that play near the trees so I've been hesitant to get to agressive, it doesn't bother the tree, just me, should i get over it and leave it or is there something I can use w/o going the chemical route? Thanks.

I haven't any educated response, not even a guess. If it were my trees, I'd leave it alone, though.