The term ‘earth-air’ refers to the air in the vadose zone, which can be modeled as an ideal gas in a closed system, so that the volume of the earth-air varies as the atmospheric pressure (AP) fluctuates. When AP rises, the earth-air is compressed and dry external air is forced into the soil. Conversely, when AP drops, the earth-air expands and moist earth-air enters the atmosphere. In this work, conclusive proof is presented for the existence of earth-air passive breathing. This is accomplished by using an innovatively-designed trap to monitor the relative humidity of the soil and showing that these moisture records contain fingerprints that are characteristic of passive breathing. It is found that the relative humidity in the soil is negatively correlated with the atmospheric fluctuations, yielding a correlation coefficient of up to-0.70. This is revealed the universal exchange between the earth-