Birch (betula) pollen incidence in france (1987-1990)

An analysis of the pollen content in the air in six French towns (Besancon, Nancy, Strasbourg, Paris, Amiens and Lyon) since 1987 has provided a comparison of the characteristics of the birch (Betula) pollen season. Single and multiple correlation methods associating both pollen and climatic parameters (particularly air temperature) were tested. The starting dates of the pollen season were observed in the six stations and compared with the estimated dates using different methods. Good correlation coefficients were obtained if the data from the year 1990, when exceptional climatic conditions prevailed, are excluded.