050 parts for every million (or fifty parts per billion). Devices that produce a lot more than this cannot be bought or shipped to California. CARB certification is often a quick way to ascertain if an air ionizer produces small levels of ozone. A different identical source will be the https://allhealthmarket.com/product/home-care-2/oxygen-and-hydrogen-generator/hydrogen-water-generator-300ml-450ml-hydrogen-inhalation-machine-99-99-oxygen-and-hydrogen-generator-ionizer-home-care/