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Negative ion generator


Also listed as: Ionized air, Ion therapy, Air ionizer
Related terms
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Related Terms
  • Air ionizer, ion therapy, ionized air, negative ions, positive ions.

  • Negative ion generators are a type of electrical device that creates charged particles, called negative ions. Health benefits from ion therapy may include prevention of allergies and treatment of Seasonal Affective Disorder (SAD). Negative ions may also increase the flow of oxygen to the brain. When a negative ion generator runs continuously, it creates what is known as ionized air. Air ionizers use an electrically charged plate to create many negative ions. These plates add an electron to many types of gasses in the air.
  • Positive ions have been suggested to have negative health effects, such as dry eyes, depression, and unclear thinking. Common household devices that generate positive ions are appliances such as hair dryers. Some advocates of negative ion generators claim that the positive ions generated by common household devices cause subtle changes in the body's chemistry, which may manifest as any number of symptoms.
  • Negative ion generators may also attract microbes and dust to their electrically charged plates. The circulation of disease-causing microbes and allergens in the area may therefore decrease.
  • Ion therapy became popular in the 1970s when a researcher published several scientific articles which attributed an improvement in several breathing problems to the placement of air ionizers in the area.
  • Today, air ionizers are sold in some mainstream specialty and department stores. Air ionizers are more popular in Japan and Eastern Europe than they are in the United States and Western Europe.
  • Though air ionizers are sold on the premise that they may prevent and reduce the severity of respiratory problems, such as allergic bronchitis, allergic sinusitis, asthma, chronic obstructive pulmonary disease, and hay fever, high quality medical trials using air ionizers to treat these conditions are lacking. More information is needed before a strong clinical recommendation can be made.
  • Recent research has investigated the use of air ionizers for the treatment of Seasonal Affective Disorder, a type of yearly depression that occurs in the winter for individuals living in the Northern hemisphere and in the summer for individuals living in the Southern hemisphere.

Theory / Evidence
  • Ions are charged particles in the air. These particles hold either a positive or a negative charge. While some of these particles occur naturally, a variety of machines and electrical equipment can distribute additional negative ions into the air. Advocates of air ionizers claim that negative ions may increase the flow of oxygen to the brain and increase the body's production of serotonin.
  • Some research suggests that certain microbes and allergy-causing substances, such as animal dander, have a positive electrical charge. In addition, some advocates believe that positively charged ions themselves have negative effects on the lungs and other parts of the respiratory organs when inhaled. Some air ionizers are designed to attract and hold these positively charged ions on a bar attached to the machine while simultaneously circulating negative ions.
  • A 2006 study by Terman et al. evaluated the change in symptoms of 99 adults with seasonal depression when treated with either light or ion therapy. Of the patients treated with high density ionization therapy, 42.7% experienced significant relief of symptoms.
  • The earliest studies on the health effects of negative ions were conducted in the 1970s by an Italian researcher. However, these studies were poorly designed, so no firm conclusions can be drawn from the experiments.


Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Centers for Disease Control. .
  2. National Center for Complementary and Alternative Medicine (NCCAM). .
  3. Terman M, Terman JS. Controlled trial of naturalistic dawn simulation and negative air ionization for seasonal affective disorder. Am J Psychiatry. 2006 Dec;163(12):2126-33.

  • In order to receive ion therapy, a person must purchase an air ionizer that is appropriate for the size and air flow of their living area, work area, or hospital room.
  • Air ionizers require regular cleaning. When air ionizers are not clean, small particles in the air, such as dust and microbes, are not captured. This is because the air ionizer can only hold a certain amount of particles at once. When the air ionizer reaches its capacity, it simply begins recirculation of air. As a result, the dust particles and microbes attracted by the air ionizer will actually be circulated faster throughout the room.
  • Air ionizers are not regulated for approval by the U.S. Food and Drug Administration (FDA). However, many ionizers are sold as air filters, devices which the FDA is developing protocol for use. However, no government agency regulates air filters.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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