Experimental assessment of allergenic tree pollen deposition patterns in the paediatric nasal cavity model

Introduction
Exposure to tree pollen allergens is a significant factor in the development of allergic rhinitis across all age groups.

Aim
The aim was to evaluate the deposition of tree pollen grains in a 3D model of the paediatric nasal cavity under different flow rates.

Material and methods
An anatomical, unilateral model of the paediatric nasal cavity was used in the experiments. Five pollen types were evaluated: birch, hazel, alder (approx. 30 µm in size), pine, and spruce (60 µm in size), under stable flow rates of 2.5, 5, and 7.5 L/min per nostril. Macroscopic analysis of photographs documenting pollen deposition was enriched by custom software for quantitative assessment of pollen-covered areas.

Results
Pollen deposition exhibited significant variation among segments. The greatest segmental deposition was observed in the anterior segments of the lateral wall and septum, whereas the lowest deposition occurred in the posterior segments. Significant pollen deposits were also revealed in the anterior areas of the inferior and middle turbinates, and in the middle meatus. These results were consistent across all pollen types and flow rates, with large effect sizes. This observed pattern results from inertial impaction. The magnitude of the effect increased with both pollen grain size and flow velocity, which further limited penetration into posterior regions. Compared to adults, the dominance of the anterior parts was more pronounced in children, reflecting anatomical differences and flow dynamics.

Conclusions
These findings have important implications for assessing pollen exposure, developing intranasal interventions, and preventing allergic rhinitis symptoms in children sensitised to tree pollen allergens.