Due to its molecular structure we find a specific reaction mechanism of ozone in biological systems, which requires low doses. By contrast to disinfection, where ozone is added over a certain period of time (ct concept) until disinfection becomes effective, we must pay particular attention to concentrations and dosages so as not to increase oxidative stress in patients, e.g., those with chronic inflammatory diseases and high oxidative stress. Here we start with a deeper insight into the effect of ozone on Red Bood Cells (RBC) and the glutathione system which can be blocked at higher concentrations if needed, such as is the case in reducing the plasmodium falciparum growth. At low ozone concentrations, the RBC metabolism is activated, 2,3-diphosphoglycerate (2.3-DPG) increases and oxygen is easily released from hemoglobin, which is helpful in diabetes and sporting activities. In mononuclear cells low dose ozone acts as a redox bioregulator, e.g., by downregulating proinflammatory cytokines and oxidative stress.