Joanne Orr, age 11, of Niagara Falls, Ontario, Canada, for her question:

How does helium affect the human body?

Helium is a gaseous element and gases have their own rulebook of behavior. They are too delicate to be handled like solids or liquids and they insist on their freedom to roam. This makes their fascinating antics hard to study. Besides, the gases of pure, unpolluted air are all invisible, odorless and tasteless. The percentage of helium in this airy mixture is very, very small. So no wonder the scientists of a few generations ago never even guessed that helium exists.

Although nitrogen is the most abundant gas in the air and, helium is one of the scarcest, they are somewhat alike. Both are do nothing elements that remain aloof and refuse to associate with other elements. Under normal conditions they do not react with chemicals, even with the energetic biochemicals of the human body. The air we take in with every breath contains a large dollop of nitrogen and the tiniest smidgen of helium. Our lungs ignore these lazy gases in the mixture and grab a helping of oxygen, the very active chemical that cells use as fuel to carry on their life processes.

However, though nitrogen and helium refuse to work, the fact that they are present creates a situation. Living cells need to tame down the oxygen’s activity: The bulky nitrogen in the air stifles the fuel energy of oxygen down to a slow burning process. Helium could do this job even better, but there is not enough of it. A breath of air is 78 parts nitrogen and 21 parts oxygen. Helium accounts for only five parts in a million parts. There is not enough helium in ordinary air to dampen the enthusiasm of the oxygen and it refuses to co operate with any of the body’s chemical activities.

However, large concentrations of helium can ease suffering and even save human lives. It is more than three times lighter than nitrogen and easier to breathe. Special breathing mixtures in which helium is substituted for nitrogen are used to relieve asthmatic and bronchial patients. Similar gaseous mixtures are used by deep sea divers. Nitrogen tends to dissolve and under the immense pressure of deep water it forms bubbles in the blood stream. This causes agonizing cramps called “the bends”. Unless the sufferer spends hours in a special decompression chamber, this deep water disease may be fatal.

Helium was used to replace nitrogen in some of the Sealab experiments. However, lots of helium does strange things to the vocal cords. It sends the voice up into a high, squeaky range and reduces its purring resonance. When the aquanauts down in the Sealab telephoned upstairs, their deep, manly voices sounded somewhat like Donald Duck. Apart from this temporary side effect, helium and the human body seem to ignore each other.

Even though helium is a lazy, do nothing chemical it can be made to do useful work. It is only one seventh as dense as air    only hydrogen gas is lighter. This gives it buoyancy, a very useful quality when it comes to lifting balloons. True, if a hydrogen balloon rises 1,000 feet, its helium filled twin can rise only 930 feet. But helium is the better lifting gas because it refuses to burn and hydrogen is highly inflammable.