Occult can also be used to describe things hidden from normal view. An occult fracture in medicine merely means a fracture that cannot be seen in an X-Ray. A occult emission is one not measured in normal monitoring. It’s like a sneaky fart. ;-)
True that. But the horrible downside is going after there emissions, calling them significant - it gives the Agency an even more blank slate to hit whomever they want, regardless of verifiability.