Ion generators are devices that work by charging particles in a room, causing them to be attracted to walls, floors, tables, curtains, occupants, and more. This process is known as abrasion and can cause the particles to be resuspended in the air. Some ion generators contain a collector to draw the charged particles back to the unit. While it has been suggested that these devices provide a benefit by rectifying a hypothetical ion imbalance, no controlled study has confirmed this effect.
The terms “ionic air purifier” and “ionizer” are often 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. Unfortunately, many manufacturers and retailers continue to market and sell air ionizers despite the danger of ozone production. Ozone is a by-product of air ionizers that has been examined for nearly a century as a harmful pollutant and a known lung irritant. Some ionizers on the market try to reduce their ozone production; however, if you must purchase a specific air purifier with ionizing functions, it is best to look on the manufacturer's or retailer's store page for details on whether the device produces ozone or not, or if it is trying to reduce ozone production.
If there is no mention of ozone production, it is best to avoid buying that air purifier. It is regrettable that many manufacturers today often include ionizing features in their air purifiers simply “to 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. You can buy ionizers as separate units or as part of an ozone air purifier.
Ionizers remove particles from the air by causing them to adhere to nearby surfaces or to each other and deposit out of the air; however, 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, this gas emitted by corona discharge can be toxic to humans and the environment. The main difference between an ozone generator and an ionizer is that an ozone generator deliberately produces ozone whereas an ionizer can sometimes produce ozone as a by-product. An ozone generator produces ozone that attacks odor-causing gases through a process called oxidation and permanently removes odor.
This is very different from a negative ion generator 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.
