 A randomized study to evaluated the safety and effect of nasal carbon dioxide on nasal congestion using acoustic rhinometry in subjects with perennial allergic rhinitis. The acoustic rhinometry is an instrument that will be used to assess the levels of the nasal congestion in each subject. Approximately 20 men and women ages 19-65 years old who have a history consistent with perennial allergic rhinitis requiring pharmacology for at least 2 years and meet all other eligibility criteria will be enrolled in this study. There will be six 6 visits to the clinic. There will be a screening visit, four 4 treatment visits, and an end of study visit. A subjects participation in the study may last up to 58 days. There will be four different doses given in this study. Each subject will receive 3 different doses of the study drug and one dose of the placebo. 