Quantitative trends in airborne loads of Celtis sinensis pollen and associations with meteorological variables in a subtropical Australian environment

Celtis sinensis is an introduced plant species to the southeastern region of Queensland that has had a destructive affect on indigenous plant communities and its pollen has been identified as an allergen source. Pollen belonging to C. sinensis was sampled during a 5-year (June 1994-May 1999) atmospheric pollen-monitoring programme in Brisbane, Australia, using a Burkard 7-day spore trap. The seasonal incidence of airborne C. sinensis pollen (CsP) in Brisbane occurred over a brief period each year during spring (August-September), while peak concentrations were restricted to the beginning of September. Individual CsP seasons were heterogeneous with daily counts within the range 1-10 grains m-3 on no more than 60 sampling days; however, smaller airborne concentrations of CsP were recorded out of each season. Correlation co-efficients were significant each year for temperature (p<0.05), but were less consistent for precipitation (p>0.05) and relative humidity (p>0.05). A significant relationship (r2=0.81, p=0.036) was established between the total CsP count and preseasonal average maximum temperature; however, periods of precipitation (>2mm) were demonstrated to significantly lower the daily concentrations of CsP from the atmosphere. Given the environmental and clinical significance of CsP and its prevalence in the atmosphere of Brisbane, a clinical population-based study is required to further understand the pollen's importance as a seasonal sensitizing source in this region.