Abstract: The relationship between the relative air humidity （RH） and methacholine （MCH）-induced airway reactivity was studied in sedated and ovalbumin-sensitized mice. The re-sults showed that the wheezing symptoms induced by MCH in lower RH groups were more severe than those in the higher RH groups. It is suggested that the air RH at 55%-75% is more suitable for this testing.

Key words: Relative humidity, Airway reactivity, Methacholine, Mouse