Thanks Swoop223, I wasn't able to find anything either so thought I would post the question just in case anybody had done any research. With the push for companies to become Carbon neutral etc and people reading about lithium-ion and fuel cells for lift trucks, thought I would start preparing my answers where possible.

i did a fair amount of research on hydrogen cell applications and to be blunt, there is not any information on what you are inquiring. Plenty of information on automotive and industrial (trucking) applications and some on forklift, but nothing for the specifically rated EX.
Being all EX rated trucks today have to be sealed up everywhere there may be a connection that may spark i have found nothing so far related to HFC's in this area. All the information i have found tout on and on about how efficient they are compared to NG or LP or Gasoline or diesel power but that's where they seem to be concentrating their information on. They speak of efficency quite a bit and even safety but they do not elaborate enough in any detail about specifics such as environments like the ones that require EX rated equipment.
At least none that i can find.