Pollen count and exhaled nitric oxide levels in a seasonal allergic rhinitis patient.

The subject was a 52-year-old man with Japanese cedar pollinosis, which developed between February and May. He had no history of asthma and was an ex-smoker. He underwent fractional exhaled nitric oxide (FeNO) measurements twice a week from 2010 to 2012. The pollen counts in 2010 were the lowest during the last decade, and the FeNO level was less than 30 ppb for the whole year. In contrast, the mean pollen count in 2011 was very high and the patient's FeNO level rose to more than 100 ppb. The mean pollen count in 2012 was comparable with that of 2010; however, high counts were detected in April and May, and the FeNO level rose to 70 ppb during the latter stages of the pollen season. These results indicate that pollen counts should be taken into consideration during the interpretation of FeNO data in asthma or allergic rhinitis.