The ionizer helps with revitalizing the air by infusing it with negative ions. The negative ions attach to particles which gives the particles an electrical charge, causing them to clump together and allow them to be more easily captured by AirDoctor.
Some ionizers are known to create high-level ozone. The AirDoctor ionizer will only increase the ozone level by a very small amount. The increase of ozone has been tested to be 0.001 ppm (Parts Per Million) = 1 ppb with the Ionizer turned on. This level is nearly unmeasurable as it is on the edge of detection limits of sophisticated electronic measurement equipment. The typical background level of Ozone in our environment is much higher than what is created by AirDoctor with the Ionizing function turned on. The recommended upper limits for ozone exposure is 0.050 ppm.
If ozone is of concern we recommend that the user does not activate the ionizer while using AirDoctor. AirDoctor emits NO ozone with the ionizer off and only one one-THOUSANDTH of one part per MILLION with the ionizer on.
AirDoctor is certified by the California Air Resource Board (CARB) to meet ozone emission limits. Note that the regulation put in place by CARB was in direct response to the dangerous ozone-generating air purifiers of 15 years ago.
https://www.arb.ca.gov/research/indoor/aircleaners/certified.htm
Certification is under the name AirDoctor.