The purpose of this study is to better understand the way in which CO2 (carbon dioxide)
affects the symptoms of allergic rhinitis or hayfever.
Our intent is to determine if CO2 has an effect on nasal challenge with antigen as a
predictor of whether it will have a beneficial effect on the treatment of seasonal allergic
1. Males and females between 18 and 45 years of age.
2. History of grass and/or ragweed allergic rhinitis.
3. Positive skin test to grass and/or ragweed antigen.
4. Positive response to screening nasal challenge.
1. Physical signs or symptoms suggestive of renal, hepatic or cardiovascular disease.
2. Pregnant or lactating women.
3. Upper respiratory infection within 14 days of study start.