Some Aspects of Temperature, Moisture And Heat Relationships in The Upper Respiratory Tract

The Air-Conditioning Capacity of the Human Nose

“…Moreover, the nose can efficiently handle a large spectrum of different environments with about over 90% efficacy (Table 4) as shown by previous experimental data. 5,4,23 In the present study the inspiratory phase was approximated by a time-dependent sinusoidal variation. In order to investigate nasal air-conditioning during exercise it is necessary to increase both the breathing rate and the tidal volume, which render the software unstable, probably due to generation of turbulence during the deceleration phase.…”

“…It has been demonstrated that during quiet breathing through the nose ambient air at 20-25 • C (i.e., dry bulb temperature) was conditioned up to 34 • C and 80% relative humidity (RH) by the time it reached the pharynx. 5,22,28,33 A healthy human may consume up to 350 kcal of heat and 400 ml of water per day in order to condition the inspired air at moderate environmental conditions. 4 Measurements in a very cold environment (e.g., -18 • C) revealed heating of the inspired air to about 30 • C by the time it reached the pharynx.…”

Air-conditioning characteristics of the human nose

“…The pressure drop across the nasal cavity is estimated to be between 0.3 to 1.3.cmH 2 O. 8 The main physiological functions of the nose are: 2,4,[8][9][10][11][12][13] (1) Filtration Nearly all particles greater than 5.m m and about 50 per cent of those from 2-4.m m in size are deposited on the ciliated mucosa and are propelled towards the pharynx so that they can be swallowed or expectorated within 15 minutes. Particles less than 2.m m pass through the nose into the lower airways;…”

“…258 C and 50 per cent relative humidity), and about a third of that is recovered during expirations. 10,11,26 In vivo measurements of air temperature within the upper respiratory tract throughout the respiratory cycle were acquired with a thermocouple that was introduced via the nose during bre-optic bronchoscopy. 13,25,[27][28][29] A representative summary of temperature and humidity distribution in the respiratory tract (Table I) for a healthy adult during quiet breathing at room temperature (228 C and 50 per cent relative humidity) shows that the nasal cavity heats the inspired air to about 348 C. 13,25,27,28 Inspiration of very cold air (e.g.…”

Theoretical Lung Deposition of Hygroscopic NaCl Aerosols

“…Morrow (1981) extensively reviewed the various attempts to estimate the relative humidity and its effect on particle growth and deposition. An early estimate of the relative humidity is 96% at a temperature of 37°C (Wilson and Lamer, 1948;Cole, 1953;Milburn et al, 1957). Later investigations (Walkenhorst and Dautrebande, 1961;Ferron, 1977;Covert, 1979;Martonen and Patel, 1981) show, however, that this estimate is too low, and a higher value of 99% or 99.5% seems to be generally accepted.…”