Adequate air conditioning in the nasal airways is mandatory for respiration and gas exchange in the lower respiratory tract. The aim of the present study was to measure relative humidity and temperature in the airstream at different sites within the nasal cavity for mapping of relative humidity and temperature in the upper airways.Intranasal relative humidity and temperature of 23 volunteers was measured during respiration at different locations in the nasal cavity.The end-inspiratory temperature and humidity data, obtained with a miniaturized thermocouple and a capacitive humidity sensor, were determined.A high increase of humidity and temperature at the end of inspiration, in relation to the environmental conditions, was found in the anterior nasal segment. The further increase of both parameters between turbinate area and nasopharynx was less pronounced in spite of the longer distance.The anterior part of the nasal cavity contributes within a short nasal passage to air conditioning of inspired air.