In a study conducted by Columbia University, 25 people with SAD (Seasonal Affective Depression) sat in front of a negative ion air purifier for a half hour every morning for a month. Half the subjects were given a low level of negative ions, and the other half a high level. The higher level of negative ion treatment proved to be as effective against SAD as antidepressants, such as Prozac and Zolof, and without the side effects of these drugs (Finley, 1996).

Negative ions for a positive attitude:
Positive ions, which are found in abundance in most indoor environements, cause an overproduction of serotonin. Serotonin is a neurotransmitter that helps the body deal with mental, emotional, and physiological stress. An overproduction initially causes hyperactivity, which rapidly leads to anxiety, and in some cases depression. Negative ion treatment has proven to be successful in reducing the overproduction of serotonin, and therefore successful in alleviating depression in some cases (Kreuger, 1957).