Background and Objective: Platanus hispanica trees are considered an important source of airborne pollen allergens in many cities of Western Europe. As the prevalence of sensitization to this species is 8% to 9% in northwestern Spain, our objective was to propose models predicting both the onset of the pollen season and the mean daily pollen concentrations.

Methods: Airborne P hispanica pollen was monitored from 1993 through 2002 with 2 Hirst volumetric spore traps in Ourense and Santiago de Compostela in northwestern Spain. The pollination start dates were determined and the data were fi tted to predictive regression models, which were tested for the year 2002.

Results: P hispanica pollen is present in the atmosphere from March to April. The main pollination period is short with a mean duration of around 40 days. The mean maximum daily concentrations exceeded 100 pollen grains/m3. As temperature is the parameter that most influences atmospheric pollen levels, this variable was chosen as the basis for models predicting both the onset of the pollen season and daily pollen concentrations. The predicted onset date was a few days later than the real start date in 2002. However, the model gave an accurate prediction of the mean daily pollen concentration.

Conclusions: The mean daily concentrations of P hispanica pollen are high, and given the allergenic potential of this species, it should be taken into account as one of the most important local spring allergens. The weather-related models proposed help us to predict P hispanica pollen concentrations in the atmosphere.

Key words: Platanus species. Pollen. Aerobiology. Aeroallergen. Spain. Air temperature. Flowering onset.