Helium is a colorless, odorless, non-flammable gas. It's completely inert, doesn't normally bind to other elements or compounds, and helium is so low in the air that we inhale a little bit when we breathe, so it's harmless even if it gets into our bodies.

But inhaling a lot of helium can lead to a lack of oxygen, so it's bad for you.

If a large amount of helium is inhaled accidentally, the oxygen in the body will be replaced by helium gas, resulting in hypoxia (the respiratory reflex is driven by excess carbon dioxide in the body and is not sensitive to hypoxia), and even death by suffocation in severe cases.

In addition, if helium is breathed directly into a high-pressure cylinder, its high flow rate can seriously damage lung tissue. Large amounts of high pressure helium and oxygen can cause symptoms of high pressure stress, but a small amount of nitrogen can deal with the problem.

Most gases normally do not cause harm to human body, but if inhaling a large amount of helium will reduce the concentration of other gases in the body, reduce the partial pressure of oxygen, leading to the overflow of oxygen in the tissues, easy to cause tissue hypoxia. So don't take in too much helium when the sound changes. Don't take in more than 10 inches of helium, and don't take in too much helium in a short period of time.