050 parts for every million (or fifty parts per billion). Devices that produce a lot more than this cannot be sold or shipped to California. CARB certification is often a quick way to find out if an air ionizer creates very low amounts of ozone. Yet another similar resource would https://allhealthmarket.com/product/home-care-2/hydrogen-generator/hydrogen-water-generator-300ml-hydrogen-inhalation-machine-h2-inhaler-therapy-hydrogen-gas-generator-water-purifier-ionizer/