An ozone generator turns molecules of oxygen into ozone, a molecule consisting of three oxygen atoms. It uses corona discharge to achieve that. An air purifier cleans the air by running it through filters that remove dust particles.
An ozone generator creates ions, charged molecules using corona discharge. A corona discharge is small but has an intense electrical field. As molecules pass through it, they pick up an extra electron, making them negatively charged. Alternatively, the molecules may lose an electron, making them positively charged.
Air particles such as dust may be ionized since they are targets for the electrons. Oxygen molecules are split into separate atoms as they pass through the corona discharge. Some of the oxygen atoms combine to form ozone.
An air purifier cleans air using filters made of foam, fiberglass, synthetic fibers or cotton. The density of the filter component controls the size of particles passing through it. Pleated filters are the best since they have increased surface area for trapping particles.
Air filters can either be High-Efficiency Particulate Air, or HEPA, or Ultra-Low Penetration Air, or ULPA. HEPA allows particles of 0.3 micrometers to pass through. ULPA allows particles of less than 0.3 micrometers to penetrate through. HEPA and ULPA can catch dust particles and allergens.