The impact of electromagnetic fields on the composition of air and its effect on living organisms was studied by the Russian biophysicist A.L. Chizhevsky at the beginning of the 20th century. He also developed the first model of the ionizer («Chizhevsky’s Chandelier»), but the mass production of ionizers for home use began only in the 90s of the 20th century.
The classical ionizer is arranged as follows. A high negative DC voltage is applied to the needle (an electrode with a small radius of curvature). Under the influence of an electric field, electrons are emitted (emission) from the tip of the needle. The emitted electrons can either join oxygen molecules (a negative ion is formed), or knock out an electron from a nitrogen or oxygen atom (impact ionization — a positive ion is formed). Negative air ions scatter from the tip of the needle to the second, positive electrode, in the direction of the electric field lines of force. The electrons knocked out of the atoms, in turn, can also form an ion. Thus, the space between the positive and negative electrodes is saturated with light ions. Moreover, the concentration of these ions is maximum near the needle and decreases with distance from it. Near the needle, you can even feel the flow of ions — the ionic wind, in the form of a weak stream of cool air.
Currently on the market there are a large number of unipolar ionizers , in which there is no positive electrode, an electrostatic field is created between the negative electrode and the floor, walls, ceiling. The dust around the unipolar ionizer is charged, forming heavy ions that are unhealthy. These charged particles move in the direction of the field lines from the ionizer to the nearest surface (walls, floor, ceiling, batteries — depending on where the device is located). After a while, all this dust settles on the surfaces, and you can safely breathe air saturated with light ions. But a unipolar ionizer should not be kept on all the time, because after a few minutes a person and things around him acquire a charge due to the deposition of negative ions and an electric field arises that repels ions of the same sign with him, and therefore further ionization of the air becomes useless.
Household air ionizers: all models
Unipolar ionizers are not recommended by the sanitary standards of the Ministry of Health of the Russian Federation, in any case, when using them, the following rules should be observed:
place the ionizer where the settled dust can be easily washed off (on the floor, on the table — but not on the ceiling)
do not stay in the room immediately after turning on the ionizer until the dust from the air settles
do not turn on the ionizer with open windows — it will draw in dust from the street
do wet cleaning more often in the room in which the ionizer is located
do not buy devices with too high output voltage (more than 20 kV) for small rooms — they create too strong a field and can damage you and cause damage to various home electronics
do not keep the ionizer on all the time
Better meet hygiene standards bipolar ionizers that produce both positive and negative ions at the same time. They can be kept on 24 hours a day if they are set up correctly and do not produce excessive amounts of ions. A bipolar ionizer, unlike a unipolar one, does not create an electrostatic field, and if an electrostatic field was already in the room, it neutralizes it. But a bipolar ionizer costs much more than a unipolar one.
And if you want to not only clean the air of dust and fill it with ions, but also get rid of odors, viruses, and other pathogens, you might want to immediately purchase air cleaner with electrostatic filter or built-in ionizer.
All ionizers emit ozone during operation, which has a bactericidal effect and is even useful in small quantities, but if the permissible limits are exceeded, it can lead to poisoning. Therefore, no matter what you choose, remember that a poorly made, not properly controlled ionizer can cause serious harm to your health. You should not buy them from little-known companies with a dubious reputation.