Fifteen non-smokers (males and females between the ages of 18 and 65 years) with physician-diagnosed moderate persistent asthma will be recruited for the study. The subjects will be allowed to use inhaled controller (including ICS) and rescue medication. At study entry, all asthmatic subjects must be clinically stable, and have a forced pre-bronchodilator one-second expired volume (FEV1) of < 75% predicted.