We performed a prospective observational study to establish a relationship between pollen counts of Chenopodiacea/Amaranthacea and clinical symptoms of rhinoconjunctivitis and asthma in a group of monosensitised patients.

Material and Methods. A total of 60 patients (19 with asthma) were included in the study. All patients collected daily symptom scores during the summer months of 1999, 2000 and 2001. The questionnaire included ocular, nasal and pulmonary symptoms. Pollen counts were expressed as pollen grains/m3. Symptom scores and pollen counts were correlated using correlation coefficients and Log transformed variables.

Results: In the 3 seasons studied we identified a peak of pollen and clinical symptoms in the second half of August and first half of September . In 1999, there was a significant positive correlation between total symptoms and daily pollen grains/m3 (p<0.005, r = 0.347). This correlation was not significant for the summers of 2000 and 2001.
After further analysis, and by displacing one of both variables between 11 to 17 days, the correlation coefficients for total symptoms, improved for 1999 (r = 0. 744; p < 0.0001) and became significant for 2000 (r = 0. 521; p < 0.0001) and 2001 (r = 0.635; p < 0.0001).

Conclusion: We identified a significant time lag between pollen counts and symptom scores in S. kali monosensitized patients.