It likes to recombine with oxygen at the slightest provocation. Ignition energy in optimum concentration with O2 (or air) is 1.2J, the same as a ten cent piece

It likes to recombine with oxygen at the slightest provocation. Ignition energy in optimum concentration with O2 (or air) is 1.2J, the same as a ten cent piece falling on it's face from edge. I've worked near a cold vent for hydrogen (eg disposed of to atmosphere, not deliberately flared) and you could hear when it used to ignite at the hint of any atmospheric electricity that was even over the horizon and not visible on a clear blue day.