How Much Air We Breathe

An estimate of about 18–20 kg of air per day is plausible for a typical adult under particular assumptions about breath volume and breathing rate. For example, 14,400 liters of air per day weigh about 17 kg at a density near 1.2 kg/m³. This is air passing through the respiratory tract; a person does not “consume” all of its mass—much of it is exhaled again. The volume depends on body size, activity, and conditions. [1–2]