Normal arterial levels of CO2 have antioxidant properties. Indeed, a group of Russian microbiologists discovered that "CO2 at a tension close to that observed in the blood (37.0 mm Hg) and high tensions (60 or 146 mm Hg) is a potent inhibitor of generation of the active oxygen forms (free radicals) by the cells and mitochondria of the human and tissues" (Kogan et al, 1997).
As we have seen arterial hypocapnia (CO2 deficiency) causes tissue hypoxia that trigger numerous pathological effects. Cell hypoxia is the main cause of free radical generation and oxidative stress and CO2 deficiency in the blood is one of the main causes of hypoxia (low oxygen).
Having a normal level of CO2 in the lungs and arterial blood (40 mm Hg or about 5.3% at sea level) is imperative for normal health. Do modern people have normal CO2 levels? When reading the table below note that levels of CO2 in the lungs are inversely proportional to minute ventilation rates, in other words, the more air one breaths the lower the level of alveolar CO2.