I would note that 30dB muffs over 30dB plugs does not provide anything even remotely close to 60dB reduction. It’s more like 33dB, because both muffs and plugs block only noise propagated through the auditory canal. They do not block noise conducted to the cochlea by bone.

At noise levels above ~140dB, no amount of PPE is capable of reducing noise to “safe” levels.