Air ioniser
Encyclopedia
An air ioniser is a device that uses high voltage
to ionise
(electrically charge) air molecule
s. Negative ions, or anions, are particles with one or more extra electron
s, conferring a net negative charge to the particle. Cations are positive ions missing one or more electrons, resulting in a net positive charge. Most commercial air purifier
s are designed to generate negative ions. Another type of air ioniser is the ESD ioniser (balanced ion generator) used to neutralise static charge.
Russian scientist and inventor Alexander Chizhevsky
produced the so called Chizhevsky Chandelier around 1918. This was the first modern air ioniser.
s. Airborne particles are attracted to the electrode in an effect similar to static electricity
. These ions are de-ionised by seeking earthed conductors, such as walls and ceilings. To increase the efficiency of this process, some commercial products provide such surfaces within the device.
The frequency of nosocomial infection
s in British hospitals prompted the National Health Service
(NHS) to research the effectiveness of anions for air purification.
The SARS
Pandemic fuelled the desire for personal ionisers in the Far East, including Japan
(where many products have been specialised to contain negative ion generators, including toothbrush
es, refrigerator
s, air conditioners, air cleaners and washing machine
s). There are no specific standards for these devices. Notebook producers ASUS
have now started to include air ionisers in their computers.
). Ozone generators are optimised to attract an extra oxygen ion to an O2 molecule, using either a corona discharge tube
or UV light.
Even the best ionisers will produce a small amount of ozone, and ozone generators will produce gaseous ions of molecules other than ozone, because air consists of more elements than oxygen.
At high concentrations, ozone can also be toxic to air-borne bacteria, and may destroy or kill these sometimes infectious organisms. However, the needed concentrations are toxic enough to humans and animals that the FDA
in the United States
explicitly demands ozone therapy
not be used as medical treatment,
and has taken action against businesses that fail to comply with this regulation.
Ozone is a highly toxic and extremely reactive gas.
A higher daily average than 0.1 ppm (0.2 mg/m³) is not recommended and can damage the lungs and olfactory bulb
cells directly.
, a non-profit U.S.-based product-testing magazine, reported in October 2003 that air ionisers do not perform to high enough standards compared to conventional HEPA
filters. The exception was a combination unit that used a fan to move air while ionizing it. In response to this report, The Sharper Image
, a manufacturer of air ionisers (among other products), sued Consumer's Union (the publishers of Consumer Reports) for product defamation. Consumer Reports gave the Ionic Breeze and other popular units a "fail" because they have a low Clean Air Delivery Rate
(CADR). CADR measures the amount of filtered air circulated during a short period of time, and was originally designed to rate media-based air cleaners. The Sharper Image claimed that this test was a poor way to rate the Ionic Breeze, since it does not take into account other features, such as 24-hour a day continuous cleaning, ease of maintenance, and silent operation. The U.S. District Court for the Northern District of California subsequently struck down The Sharper Image's complaint and dismissed the case, reasoning that The Sharper Image had failed to demonstrate that it could prove any of the statements made by Consumer Reports were false. The Court's final ruling in May 2005 ordered The Sharper Image to pay US$ 525,000 for Consumer Union's legal expenses.
if the negative ions are in sufficient density (quantity). Note that this is a separate issue from air cleaning claims or ozone generation that occurs in some devices that also generate negative ions.
Clinical research has been published through Columbia University, American Journal of Psychiatry/APA, 2006 and Archives of General Psychiatry, Columbia University, and New York State Psychiatric Institute, 1998 and Journal of Alternative Complementary Medicine, Columbia University 1995.
High voltage
The term high voltage characterizes electrical circuits in which the voltage used is the cause of particular safety concerns and insulation requirements...
to ionise
Ionization
Ionization is the process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions. This is often confused with dissociation. A substance may dissociate without necessarily producing ions. As an example, the molecules of table sugar...
(electrically charge) air molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s. Negative ions, or anions, are particles with one or more extra electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s, conferring a net negative charge to the particle. Cations are positive ions missing one or more electrons, resulting in a net positive charge. Most commercial air purifier
Air purifier
An air purifier is a device which removes contaminants from the air. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke...
s are designed to generate negative ions. Another type of air ioniser is the ESD ioniser (balanced ion generator) used to neutralise static charge.
Russian scientist and inventor Alexander Chizhevsky
Alexander Chizhevsky
Alexander Chizhevsky was a Soviet-era interdisciplinary scientist, a biophysicist who founded “heliobiology” and “aero-ionization”...
produced the so called Chizhevsky Chandelier around 1918. This was the first modern air ioniser.
Ionic air purifiers
Air ionisers are used in air purifierAir purifier
An air purifier is a device which removes contaminants from the air. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke...
s. Airborne particles are attracted to the electrode in an effect similar to static electricity
Static electricity
Static electricity refers to the build-up of electric charge on the surface of objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge. Static electricity can be contrasted with current electricity, which can be delivered...
. These ions are de-ionised by seeking earthed conductors, such as walls and ceilings. To increase the efficiency of this process, some commercial products provide such surfaces within the device.
The frequency of nosocomial infection
Nosocomial infection
A nosocomial infection , also known as a hospital-acquired infection or HAI, is an infection whose development is favoured by a hospital environment, such as one acquired by a patient during a hospital visit or one developing among hospital staff...
s in British hospitals prompted the National Health Service
National Health Service
The National Health Service is the shared name of three of the four publicly funded healthcare systems in the United Kingdom. They provide a comprehensive range of health services, the vast majority of which are free at the point of use to residents of the United Kingdom...
(NHS) to research the effectiveness of anions for air purification.
The SARS
Severe acute respiratory syndrome
Severe Acute Respiratory Syndrome is a respiratory disease in humans which is caused by the SARS coronavirus . Between November 2002 and July 2003 an outbreak of SARS in Hong Kong nearly became a pandemic, with 8,422 cases and 916 deaths worldwide according to the WHO...
Pandemic fuelled the desire for personal ionisers in the Far East, including Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
(where many products have been specialised to contain negative ion generators, including toothbrush
Toothbrush
The toothbrush is an oral hygiene instrument used to clean the teeth and gums that consists of a head of tightly clustered bristles mounted on a handle, which facilitates the cleansing of hard-to-reach areas of the mouth. Toothpaste, which often contains fluoride, is commonly used in conjunction...
es, refrigerator
Refrigerator
A refrigerator is a common household appliance that consists of a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room...
s, air conditioners, air cleaners and washing machine
Washing machine
A washing machine is a machine designed to wash laundry, such as clothing, towels and sheets...
s). There are no specific standards for these devices. Notebook producers ASUS
ASUS
ASUSTeK Computer Incorporated is a multinational computer technology and consumer electronics product manufacturer headquartered in Taipei, Taiwan. Its product range includes motherboards, desktops, laptops, monitors, tablet PCs, servers and mobile phones...
have now started to include air ionisers in their computers.
Ions versus ozone
Ionisers should not be confused with ozone generators, even though both devices operate in a similar way. Ionisers use electrostatically charged plates to produce positively or negatively charged gas ions that particulate matter sticks to (in an effect similar to static electricityStatic electricity
Static electricity refers to the build-up of electric charge on the surface of objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge. Static electricity can be contrasted with current electricity, which can be delivered...
). Ozone generators are optimised to attract an extra oxygen ion to an O2 molecule, using either a corona discharge tube
Corona discharge
In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor that is electrically energized...
or UV light.
Even the best ionisers will produce a small amount of ozone, and ozone generators will produce gaseous ions of molecules other than ozone, because air consists of more elements than oxygen.
At high concentrations, ozone can also be toxic to air-borne bacteria, and may destroy or kill these sometimes infectious organisms. However, the needed concentrations are toxic enough to humans and animals that the FDA
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
explicitly demands ozone therapy
Ozone therapy
Ozone in the stratosphere deflects harmful solar radiation, but ground level ozone has well-studied and cumulative deleterious health effects. The use of ozone therapy is advocated as a form of alternative medicine but there is no scientific evidence supporting its use in treatment of specific...
not be used as medical treatment,
and has taken action against businesses that fail to comply with this regulation.
Ozone is a highly toxic and extremely reactive gas.
A higher daily average than 0.1 ppm (0.2 mg/m³) is not recommended and can damage the lungs and olfactory bulb
Olfactory bulb
The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...
cells directly.
Consumer Reports court case
Consumer ReportsConsumer Reports
Consumer Reports is an American magazine published monthly by Consumers Union since 1936. It publishes reviews and comparisons of consumer products and services based on reporting and results from its in-house testing laboratory. It also publishes cleaning and general buying guides...
, a non-profit U.S.-based product-testing magazine, reported in October 2003 that air ionisers do not perform to high enough standards compared to conventional HEPA
HEPA
High-Efficiency Particulate Air or HEPA is a type of air filter. Filters that are awarded the HEPA accolade are used in various locations, whether in medical facilities, automotive vehicles, airplanes, home filters, or wherever very pure air is sought. The filter must satisfy certain standards of...
filters. The exception was a combination unit that used a fan to move air while ionizing it. In response to this report, The Sharper Image
The Sharper Image
The Sharper Image is an American product brand, formerly associated with a defunct retail company, now licensed for use on consumer electronics and gift products....
, a manufacturer of air ionisers (among other products), sued Consumer's Union (the publishers of Consumer Reports) for product defamation. Consumer Reports gave the Ionic Breeze and other popular units a "fail" because they have a low Clean Air Delivery Rate
Clean Air Delivery Rate
Clean-air delivery rate indicates the volume of filtered air delivered by a portable air cleaner. Whole house air cleaners are not covered by the CADR specification therefore CADR claims for whole house air cleaners are not comparable with CADR ratings for portable air cleaners. CADR also...
(CADR). CADR measures the amount of filtered air circulated during a short period of time, and was originally designed to rate media-based air cleaners. The Sharper Image claimed that this test was a poor way to rate the Ionic Breeze, since it does not take into account other features, such as 24-hour a day continuous cleaning, ease of maintenance, and silent operation. The U.S. District Court for the Northern District of California subsequently struck down The Sharper Image's complaint and dismissed the case, reasoning that The Sharper Image had failed to demonstrate that it could prove any of the statements made by Consumer Reports were false. The Court's final ruling in May 2005 ordered The Sharper Image to pay US$ 525,000 for Consumer Union's legal expenses.
Negative ion treatment for seasonal affective disorder
Published research shows that high levels of negative ions are a useful treatment for Seasonal Affective DisorderSeasonal affective disorder
Seasonal affective disorder , also known as winter depression, winter blues, summer depression, summer blues, or seasonal depression, is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or summer, spring or autumn...
if the negative ions are in sufficient density (quantity). Note that this is a separate issue from air cleaning claims or ozone generation that occurs in some devices that also generate negative ions.
Clinical research has been published through Columbia University, American Journal of Psychiatry/APA, 2006 and Archives of General Psychiatry, Columbia University, and New York State Psychiatric Institute, 1998 and Journal of Alternative Complementary Medicine, Columbia University 1995.
See also
- Electrostatic precipitatorElectrostatic precipitatorAn electrostatic precipitator , or electrostatic air cleaner is a particulate collection device that removes particles from a flowing gas using the force of an induced electrostatic charge...
- HumidifierHumidifierA humidifier is a household appliance that increases humidity in a single room or in the entire house. There are point-of-use humidifiers, which are commonly used to humidify a single room, and whole-house or furnace humidifiers, which connect to a home's HVAC system to provide humidity to the...
- Negative air ionization therapyNegative air ionization therapyNegative air ionization therapy is the use of air ionisers as an experimental non-pharmaceutical treatment for seasonal affective disorder and mild depression....
- Seasonal affective disorderSeasonal affective disorderSeasonal affective disorder , also known as winter depression, winter blues, summer depression, summer blues, or seasonal depression, is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter or summer, spring or autumn...
- Negative ion
- Nebuliser
External links
- New Scientist – Air ionisers wipe out hospital infections
- Do "corona discharge" devices alleviate asthma?
- Overview of electrofilter precipitator
- NIOSH Immediate Danger to Life or Health (Ozone) Documentation
- Ionic Air Purifiers and Smog
- The Negative-Ion Myth
- Ionisers in the workplace information
- Air ion behaviour in ventilated rooms Indoor and Built Environment, 17 (2). pp. 173–182., Fletcher, L.A., Noakes, C.J., Sleigh, P.A., Beggs, C.B. and Shepherd, S.J. (2008)