Physiologically, the presence of negative ions in a sweat bath is as important as the heat. The discovery of negative ions in certain types of saunas a few years ago became headline news in Finland. Until then, the healing power of the sauna was attributed to relaxation and increased circulation. Now, negative ions add startling new possibilities.

Since the early 1950s scientists have suspected that ions play an important role in how the body functions and, consequently, in how we feel. Research has shown that an abundance of negative ions in the air we breathe is highly beneficial, while a lack of ions or a higher ratio of positive to negative can cause physical harm. The role played by ions in everyday life has become intensely topical among researchers in the medical profession.

An ion is simply a molecule with an electric charge, either positive or negative. Ionization, or ion formation, occurs when enough energy acts on a molecule to cause it to discharge an electron. Because electrons carry a negative charge, the molecule stripped of an electron has a greater positive charge and becomes a positive ion. The lost electron scoots around loose until it attaches itself to another molecule which causes the new molecule to become negatively charged--a negative ion.

Radioactive substances in the earth's crust and cosmic rays cause most ionization. But fire, crashing water (like water falls and surf), and plants during photosynthesis can produce negative ions as well. Europeans take ion depletions seriously and simple negative ion generators have been installed in many businesses, banks, hospitals, and passenger cars and even airliner cockpits. Furthermore, in this country, Europe and the Soviet Union, negative ion therapy has been used in treatments to help burn victims heal faster, to cure respiratory diseases, to rid the body of general infections, and even to check the spread of some cancers.

Conversely, scientists have found that if the air is charged with too few negative ions and too many positives, we become anxious, fatigued and tense. This condition is known as "pos-ion poisoning," and often occurs as the result of weather disturbances, central air conditioning, smog, and driving too long within the confines of an automobile. Pos-ion poisoning has, in fact, been linked to heart attacks, aggravated asthma, migraine headaches, insomnia, rheumatism, arthritis, hay fever, and most allergies.

The effect of negative ions on sweat bathing was discovered when researchers were trying to account for the tremendous popularity of sauna wood burning stoves over electric stoves. Subjective reasons, such as the fragrance of burned wood, did not fully explain why Finns felt so refreshed after time in a wood heated sauna and quite dulled, from certain electrically heated saunas. Tests showed that the practice of splashing water on super-heated rocks produced an abundance of negative ions.

Many electric stoves, it turned out, were not getting the rocks hot enough and the glowing metal heating coils were spurting more positive ions in the air. Researchers learned that if the rocks were properly heated in electric stoves, the positive ions, being larger and less mobile, would ground out on the hot stones.