We have developed a method for measuring the temperature and relative humidity of air prior to and after nasal conditioning and used it to study the effect of treatment with ipratropium bromide on the ability of the nose to condition cold, dry air. We performed randomized, double-blind, placebo-controlled, two-way crossover studies and an open study in nonallergic subjects. The subjects were treated with ipratropium bromide (84 microgram) or normal saline solution sprayed into the nasal cavity 15 min before the measurement of nasal conditioning capacity. Cold, dry air was delivered to the nose via a nasal mask, and the temperature and humidity of air were measured before entering and after exiting the nasal cavity. The total water gradient across the nose was calculated and represents nasal conditioning capacity. Ipratropium bromide treatment significantly increased nasal conditioning capacity when compared with saline. Ipratropium bromide led to less reduction in the cold, dry air-induced decrease in the nasal volume (p < 0.05) without affecting the decrease in nasal surface temperature during cold, dry air exposure (p = 0.3). Our data show that ipratropium bromide increases the ability of the nose to condition cold, dry air. Thus, treating rhinitis with ipratropium bromide should not increase the burden for inspired air conditioning on the conducting pulmonary airways.