Ion generators work by charging particles in a room so that they are attracted to walls, floors, tables, curtains, occupants, etc. Abrasion can cause these particles to resuspend in the air. In some cases, these devices contain a collector to draw charged particles back to the unit. While ion generators can remove small particles (for example, although some have suggested that these devices provide a benefit by rectifying a hypothetical ion imbalance), no controlled study has confirmed this effect.
The fact is that both terms are used interchangeably in the market; however, they actually describe the same product. For the sake of consistency, we will refer to the general product group as an “air ionizer”, of which there are two main types that you will find on the market. Electrostatic precipitators work by dispersing charged ions into the air through the corona discharge. These ions then bind to airborne particles, which are then collected on a flat plate with opposite charge.
This is essentially what most “ionizers” on the market use, and in fact, it is often their most touted feature, because you can simply take out these plates and remove the accumulated particles, whether it's dust or other contaminants that build up in your home. Because most ionizing air purifiers produce ozone, a by-product that has been examined for nearly a century as a harmful pollutant and a known lung irritant, it can be assumed that these products have long been recalled. Unfortunately, as the self-regulated industry filled with dubious products, many manufacturers and retailers continued to market and sell air ionizers, despite the danger of ozone production. Although their scale is limited, some ionizers on the market try to reduce their ozone production.
If you must purchase a specific air purifier with ionizing functions, a good rule of thumb is to look on the manufacturer's or retailer's store page for details on whether the device produces ozone or not, or if the device is trying to reduce ozone production. If the product doesn't make any mention of ozone, you'll most likely want to avoid buying that air purifier. In fact, many manufacturers today often include ionizing features in their air purifiers to simply “populate the list of functions and justify the higher cost of the air purifier”. There is some irony in buying a product that is supposed to improve indoor air quality, but introduces a polluting by-product into your home.
It is regrettable that, despite a very public warning from a reputable consumer defense outlet, a product that can actively cause harm continues to be sold to consumers to this day. Some ozone air purifiers are made with an ion generator, sometimes called an ionizer, in the same unit. You can also buy ionizers as separate units. Ionizers remove particles from the air.
They do this by causing particles to adhere to nearby surfaces or to each other and deposit out of the air, but they can generate unwanted ozone. Indoors, ozone is produced by air ionizers (if you have one in your home). As mentioned above, ionizers commonly use corona discharge to emit negative ions. However, the gas emitted by corona discharge can be toxic to humans and the environment (.
The main difference is that ozone generators deliberately produce ozone, whereas ionizers can sometimes produce ozone as a by-product. An ozone generator produces ozone that attacks the source of odor-causing gases through a process called oxidation and permanently removes odor. This is very different from a negative ion generator, or ionizer, whose main purpose is to reduce particles such as dust and pollen that float in airspace. If you've made it this far and digested all the information about air ionizers (whether they're marketed as ionic air purifiers or ionizers), you've probably already realized that most people shouldn't buy an air purifier with an ionizing function.