Co2 Tolerance Breathing

Summary

Most people in the modern world breathe slightly too much, too fast, and through the mouth, which lowers their tolerance to carbon dioxide and biases the nervous system toward arousal; deliberately breathing *less* — nasal, slow, light, with comfortable (never near-water, never-while-driving) breath-holds — retrains CO₂ tolerance and is a genuinely useful adjunct for asthma and dysfunctional breathing, but its sold-as-everything "functional breathing" form rests on much thinner evidence than its marketing implies. ---