what you can't see can't hurt you ...
... unless it's invisible laser light that can burn your eyes right off (unverified fact). please avoid the invisible beams.
so it appears there are two sorts of dangers. those we can see and those that we can't. if we avoid both of those then we should be ok.
The very worst kind of invisible beams are those very low ones across the tops of doorways in Olde Worlde pubs