Annual variations in the concentrations ofBetulapollen in the London area, 1961–1990

Annual variations in the ambient concentrations of Betula pollen monitored by volumetric sampling at sites in London and also at a site to the South of the city between the years 1961–1990 are analysed in relation to the main meteorological parameters. Attention is focussed on variations in the start and duration of the seasons and on the annual patterns of pollen abundance. Consideration is given also to the variation in the severity of seasons. The paper examines possible rhythms in the annual production of Betula pollen and develops empirical regression models from the analyses of the trends to predict the main characteristics of the seasons.