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NORMAL man is able to function in an extremely cold environment without experiencing symptoms of respiratory difficulty or suffering injury to his airways.1 This protective ability may be due to the fact that the normal respiratory tract is highly effective in its ability to heat and humidify inspired air under extreme climatic conditions.2 Studies have shown that air delivered at the lips at -100°C. is heated to within 1 or 2° of body temperature by the time it reaches the tracheal bifurcation.3 On the other hand, patients with chronic respiratory disease, such as emphysema, bronchial asthma or chronic bronchitis, may . . .
Wells et al. (Thu,) studied this question.
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