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Oxygen supports the functionality of all body systems. Even when we exercise regularly (and most of us don’t), we do not maintain an optimal level of this gas in our bodies. Why? Because our environment is increasingly deficient in Oxygen, polluted by chemicals, exhaust fumes, industrial emissions, and burned fossil fuels. It is estimated that the Earth’s atmosphere contained 38-50% Oxygen, which has now dropped to about 20%; in some urban environments, it is even lower.