"Steve Walker" wrote in message
...
Leaks (within reason) are not too bad (except in an unventilated garage)
as unlike petrol vapour or lpg, it rises and dissipates rapidly.

I was thinking also in the sense of not wanting to find that your car has
less fuel than it had the previous day. As you say, H2 gas won't hang around
for long - it will rise and dissipate.