A hydrogen fuel cell vehicle is completely safe. It is basically water and does not have any risk of explosion. It is actually safer than a gasoline car and is much more economical. It just sounds scary because we think of a hydrogen bomb. This is not the same concept at all.
Hydrogen fuel cell vehicles require that hydrogen be compressed
and stored in a tank, increasing the danger of explosion. Of course
gasoline is flammable too, however, hydrogen is colorless and
odorless, unlike gasoline, so a leak would be harder to detect. A leak
could conceivably suffocate unwilling fuel cell users, too. Oddly,
there is also a danger of frostbite, because hydrogen is chilled to compress it.
Overall, many scientists believe it will be safer and more efficient to switch
to plug-in electric cars, rather than hydrogen fuel cell vehicles.