Hydrogen can leak thru the tightest seals.
Hydrogen makes steel brittle.
Hydrogen fires are invisible and do not generate heat "out the sides" so you can walk into a hydrogen fire without knowing until you're in it.
Hydrogen self-ignites on contact with platinum, something often found in jewelry.
Hydrogen is violently explosive in proper concentration.
etc.
Hydrogen can leak thru the tightest seals.
Hydrogen makes steel brittle.
Hydrogen fires are invisible and do not generate heat "out the sides" so you can walk into a hydrogen fire without knowing until you're in it.
Hydrogen self-ignites on contact with platinum, something often found in jewelry.
Hydrogen is violently explosive in proper concentration.
etc.