I'm curious, where are you getting your em dashes from?
My US 101 keyboard layout doesn't have it, do euro keyboard layouts with alt-gr have it relatively easily accessible? Presumably there's an alt+numpad combo, but that seems to be something that would interrupt the flow of typing quite a bit.
I've just discovered that if I go into the numeric/character section of my phone keyboard and long press the -, I can get —, but that's a long-winded way of getting them.
That's better, but it's still a mystery. Cs-137 sources should be rigorously stored, even in density gauges they are permanently inside a capsule with a shutter that turns the beam "on and off". It's not like you have a chunk of Cs-137 rattling around in a drawer somewhere (or worse, somehow in powered form that gets all over the inside of a shipping container) but that sounds like that's been the case here.
It's not the first time one of these sources has come loose though - there was a capsule lost on 1400km of highway in Western Australia a little while ago.