Yes, but only when occurring in extremely high concentrations - levels that due to the RGF's Technology, a RGF® Air Purifier is incapable of producing. The Federal Government and other agencies have set safety guidelines, Ozone concentrations of 0.05 - 0.10 ppm. The RGF® Air Purifier CANNOT produce higher than 0.04 (typically .02) ppm. Reports and studies that raise questions about the safety of ozone deal with ozone levels at or above the recommended concentrations.