Pollen data from three Burkard volumetric samplers, running simultaneously on buildings at heights of 12, 24 and 30 metres above ground level from 23rd June to 21st July 1992, were used to investigate vertical differences in pollen abundance, and correlations with six different weather parameters. Regression analysis was used to investigate the relationship between Gramineae andUrticapollen levels and the weather variables. Pollen concentrations from the 30 m trap were consistently smaller than those from the 12 and 24 m traps for all types examined. It was concluded that pollen from local sources was not sufficiently mixed in the air to reach the 30 m trap. A delay was observed in the peak concentrations of bothUrticaand Gramineae pollen between the three traps, with the maximum occurring approximately four hours earlier at 12 m than at 24 and 30 m. Circadian rhythms were also more prominent at the lower trap than at the two higher ones.Urticaand Gramineae concentrations at 12 and 24 m were correlated significantly to all the weather variables examined. Only sunshine and relative humidity were significantly correlated with pollen concentrations ofUrticaand Gramineae recorded at 30 m. Climate also affected the vertical variation in pollen concentration between the three traps. Rainfall, high wind speeds and high relative humidity reduced vertical variation, whilst warm sunny weather increased it.