Hydrogen is highly combustible.
hydrogen sulfide is not hazardous
Not really.....
hydrogen cynide
Hydrogen is released while charging.
It is hydrogen cynide , highly harmful and hazardous for life.
Scott C Steinsberger has written: 'Laboratory and field evaluation of methodology for determination of hydrogen chloride emissions from municipal and hazardous waste incinerators' -- subject(s): Environmental aspects, Environmental aspects of Hydrogen chloride, Hazardous wastes, Hydrogen chloride, Incineration
Methane and Oxygen
If consumed rubidium may be poisonous, but other wise it isn't.
Examples: sodium cyanide, phosgene, hydrogen fluoride, mercuric chloride, arsenic oxide, etc
The primary safety hazards of hydrogen are fire (and the resulting burns since a hydrogen fire is not easily visible) and explosion if the hydrogen is compressed in a cylinder. It is difficult to suffocate in hydrogen, although not impossible, because the gas is very light, rises to the ceiling, and easily exfiltrates through seams and small fissures in structures.
Dangerous in what way? hydrogen just being burned does not contribute to global warming, but what about 'making' the hydrogen? Does that use other fuels that contribute to global warming? Hydrogen is more explosive if that is what you mean by dangerous. Hydrocarbons burn to form carbon dioxide which contributes to global warming.
Some hazardous chemicals can be made non-hazardous and some cannot.