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% (~5

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.