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Original Article


Short-term Effects of Airborne Ragweed Pollen on Clinical Symptoms of Hay fever in a Panel of 30 Patients


D Caillaud,1 M Thibaudon,2 S Martin,3 C Ségala,3 JP Besancenot,2 B Clot,4 H François,1 on behalf of the French Aerobiology Network

1Service de Pneumologie, Hôpital Gabriel Montpied, 63003 Clermont-Ferrand, France
2French Network of Aerobiological Monitoring, RNSA, 69960 Brussieu, France
3Sepia-Santé, 56150 Baud, France
4Federal Office of Meteorology and Climatology MeteoSwiss, 1530 Payerne, Switzerland

J Investig Allergol Clin Immunol 2014; Vol. 24(4): 249-256



Objectives: Ragweed, Ambrosia artemisiifolia, is a highly allergenic annual herbaceous plant that is spreading quickly across the globe. Few studies have investigated the relationship between ragweed pollen counts and hay fever symptoms. We investigate the dose-response relationship between ragweed exposure in patients sensitized to ragweed and daily hay fever symptoms.

Method: A panel study was conducted among 31 adult patients sensitized to A artemisiifolia in France and Switzerland. Rhinitis, conjunctivitis, and bronchial symptoms were recorded daily, as well as daily pollen counts of ragweed, air pollutants, and meteorological data over 2 successive years. Data were analyzed with generalized estimating equation models to quantify effects of ragweed pollen whilst controlling for confounders.

Results: The relationship between ragweed pollen and the percentage of patients with nasal, ocular, and bronchial symptoms was linear. For every increase of 10 grains/m3, the odds ratio (OR) (95% confidence interval) for nasal symptoms was, in 2009, 1.18 [1.04-1.35] on weekdays and 1.43 [1.16-1.75] at weekends, and in 2010, 1.04 [1.00-1.07] on weekdays and 1.25 [1.06-1.46] at weekends. The OR for ocular symptoms was 1.32 [1.16-1.56] in 2009 and 1.05 [1.02-1.07] in 2010. Finally, the OR for bronchial symptoms was 1.14 [1.03-1.25] in 2009 and 1.03 [0.97-1.08] in 2010.

Conclusion: There is a statistically significant linear relationship between ragweed pollen counts and hay fever symptoms. Our study shows that nasal symptoms differ on weekdays and at weekends.

Key words: Air pollution. Epidemiology. Hay fever. Meteorological factors. Panel study. Pollen. Ragweed.