AirDoctor is not an ozone generator. AirDoctor has a built-in ionizer, but it is turned off by default. The ionizer helps with revitalizing the air by infusing it with negative ions. This is similar to the effect after a rainstorm or living by the sea. Some people enjoy creating this effect, but it is a completely optional feature. AirDoctor will work perfectly well if you never choose to use the ionizer option. AirDoctor does not depend on the ionizer to achieve its high-level of air purification. 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.