Even that wouldn't be such a big issue, if the flammability limit of hydrogen is from 4% to 74% in air (~20x). For comparison gasoline vapor is 1.4% to 7.6% (~5x)
In an open space that's not so bad since the flammable material literally floats away (while gasoline vapor settles), but it's still an issue in any contained area.
In an open space that's not so bad since the flammable material literally floats away (while gasoline vapor settles), but it's still an issue in any contained area.