This article is about the air purifier. For the psychiatric treatment, see Negative air ionization therapy. This photo shows the sterilisation effects of negative air ionization on a chamber aerosolised with Salmonella enteritidis. The left sample is untreated; Photo taken in a lab operated by the United States Department of Agriculture. An air ioniser (or negative ion generator or "Chizhevsky's chandelier") is a device that uses high voltage to ionise (electrically charge) air molecules. Negative ions, or anions, are particles with one or more extra electrons, 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 purifiers are designed to generate negative ions. Another type of air ioniser is the electrostatic discharge (ESD) ioniser (balanced ion generator) used to neutralise static charge. In 2002, Cecil Alfred 'Coppy' Laws was credited with being the inventor of the domestic air ioniser in an obituary in The Independent newspaper.

Air ionisers have been used to eliminate the occurrence of air-borne bacterial infections and to reduce static electricity buildup in electronics. Air ioniser and purifier with its dust collection plates removed Air ionisers are used in air purifiers to remove particles from air. 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 infections in British hospitals prompted the National Health Service (NHS) to research the effectiveness of anions for air purification, finding that repeated airborne acinetobacter infections in a ward were eliminated by the installation of a negative air ioniser—the infection rate fell to zero, an unexpected result. Positive and negative ions produced by air conditioning systems have also been found by a manufacturer to inactivate viruses including influenza.

The SARS epidemic fueled the desire for personal ionisers in East Asia, including Japan (where many products have been specialised to contain negative ion generators, including toothbrushes, refrigerators, air conditioners, air cleaners, and washing machines). my ac unit is leaking water in the atticThere are no specific standards for these devices.harga ac portable di batam Ionisers are distinct from ozone generators, although both devices operate in a similar way. ac units waco txIonisers use electrostatically charged plates to produce positively or negatively charged gas ions (for instance N2− or O2−) that particulate matter sticks to in an effect similar to static electricity. Even the best ionisers will also produce a small amount of ozone—triatomic oxygen, O3—which is unwanted.

Ozone generators are optimised to attract an extra oxygen ion to an O2 molecule, using either a corona discharge tube or UV light. At concentrations that do not exceed public health standards, ozone has been found to have little potential to remove indoor air contaminants.[3] At high concentrations ozone can be toxic to air-borne bacteria, and may destroy or kill these sometimes infectious organisms. However, the required concentrations are sufficiently toxic to humans and animals that the US FDA declares that ozone has no place in medical treatment[4] and has taken action against businesses that violate this regulation by offering therapeutic ozone generators or ozone therapy.[5] Ozone is a highly toxic and extremely reactive gas.[6] A higher daily average than 0.1 ppm (100 ppb, 0.2 mg/m³) is not recommended and can damage the lungs and olfactory bulb cells directly. A number of studies have been carried out on negative ion generators. Some studies show that the ozone generated can exceed guidelines in small, non ventilated areas.

[7] One study showed that ozone can react with other constituents to increase pollutants such as formaldehyde. Consumer Reports, a non-profit US-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 United States District Court for the Northern District of California 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. Air ionisers are sometimes used in places where work is done involving static-electricity-sensitive electronic components, to eliminate the buildup of static charges on non-conductors. Grounding with ground straps or other methods eliminates static buildup on conductors, but not non-conductors.Poor indoor air quality represents one of the top five public health risks, according to the National Institute of Environmental Health Science. With the average person spending about 90 percent of his time indoors, taking steps to improve the air quality in your home can provide significant health benefits. Ionizers and other electronic cleaning devices offer an effective solution for removing pollutants from the air, but must be chosen with care to avoid potential problems and health risks.

Both fanless and fan-based ionizers offer relief from some pollutants. Fan-based units rely on an integral fan to spread ions into the air. The fan tends to produce a high level of noise in most units, and these systems consume more energy than fanless models. Fanless models distribute ions more slowly, and thus take longer to clear the air. Without a fan, they produce less noise and consume less energy than models with a built-in fan. Consumers can choose from whole-house or room-based ionizers. A whole-house unit works with the home's central heating and cooling system, sending charged ions through the HVAC ducts. Room-based units sit on the floor in a single room, similar to a space heater. According to the North Coast Unified Air Quality Management District, central ionizers tend to operate more effectively than portable units, though room based models can be effective in some scenarios. According to the North Coast Unified Air Quality Management District, ionizers offer an effective solution for reducing asthma and allergy symptoms, but tend to be ineffective at removing gases and odors from the air.