Air normally contains a mixture of negative and positive ions. These electrically charged molecules are produced by nature from background radiation, cosmic rays, electromagnetic waves, the sun, lightning and waterfalls. These factors determine the amount of negative and positive ions in the atmosphere. Ions are formed most commonly in the soil, where trace elements of radioactive potassium, radon, and uranium initiate the ion reaction. An atom of oxygen hit by a radioactive ray immediately links up with four to six molecules of water vapor to form an ion.
Ions also form in the air when oxygen atoms are hit by cosmic rays or light rays.
Good and Bad Places Proponents of negative ion therapy believe ions can influence a person's health and well-being. They say certain parts of the world can be good or bad for people depending on the number of ions there. Places with a lot of positive ions such as polluted cities can supposedly make you restless, anxious, depressed, and raise your blood pressure. Positive ions have also been blamed for headaches, irrtability, and chest tightness. This is because they increase the body's production of serotonin which leads to adverse effects.