Hydrogen has been used in diving for more than 80 years since 1937. Comex of France in 1992 used the Oxyhydrogen to dive more than 700 metres and stay for 14 days. There are many other experiments can confirm very clearly that even high pressure hydrogen gas inhaled for many days but has no toxic side effects to the human body, and the intake of hydrogen at normal pressure is less than 1/10,000 of it, so hydrogen is very, very, very safe for humans.