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The London plane tree is frequently used in gardens, parks, and avenues in European urban areas for ornamental purposes with the aim to provide shade, and given its tolerance to atmospheric pollution. Nevertheless, unfortunately, over recent decades, bioaerosols such as Platanus pollen grains cause increasing human health problems such as allergies or respiratory tract infections. An aerobiological sampling of airborne Platanus pollen and Pla a 1 allergen was performed using two volumetric traps placed on the roof of the Science Faculty building of the city of Ourense from 2009 to 2020. A volumetric sampler Hirst–type Lanzoni VPPS 2000 (Lanzoni s.r.l. Bologna, Italy) was used for pollen sampling. Pla a 1 aeroallergen was sampled by using a Burkard Multi-Vial Cyclone Sampler (Burkard Manufacturing Co., Ltd., Hertfordshire, UK) and by means of the enzyme-linked immunosorbent assay (ELISA) technique. Data mining algorithms, C5.0 decision trees, and rule-based models were assessed to evaluate the effects of the main meteorological factors in the pollen or allergen concentrations. Plane trees bloom in late winter and spring months in the Northwestern Spain area. Regarding the trends of the parameters that define the Platanus pollen season, the allergen values fitted the concentrations of pollen in the air in most cases. In addition, it was observed that a decrease in maximum temperatures causes a descent in both pollen and allergen concentrations. However, the presence of precipitations only increases the level of allergens. When the risk of allergy symptomatology was jointly assessed for both the concentration of pollen and allergens in the study area, the number of days with moderate and high risk for pollen allergy in sensitive people increased with respect to traditional alerts considering only the pollen values. Full article

Historical pollution can be elucidated with variations of elements’ concentration in tree rings by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). However, the capacity of chemical elements’ absorption significantly depends on the tree species and element types. Metal concentrations in the rings for five species (Platanus occidentalis, Salix koreensis, Chamaecyparis obtusa, Pinus densiflora, Ginkgo biloba) were investigated in light of metal pollution history in ambient air of D industrial site located in Daejeon, Korea. The calibration for LA-ICP-MS was performed using cellulose-matrix matched standards with ¹³C normalization. Tree ring series except for Ginkgo sp. showed that the accumulation rates of Pb and Cd were higher between 1992 and 1999. Other elements, such as Fe, Cr, Mn, Cd, Zn, and Sr, showed a variation in the rings, likely due to the different physiological processes of element uptake and radial mobility. Concentrations of Pb and Cd in the annual rings of Pinus sp. corresponded to the metal monitoring data for the ambient air with the correlation coefficients of 0.879 and 0.579, respectively. Moreover, Cd in Platanus sp. and Pb in Salix sp. showed a positive correlation to ambient metal concentration compared to Chamaecyparis sp. and Ginkgo sp. Therefore, caution should be taken to select candidate elements as well as tree species to reconstruct the ambient air metal pollution history by measuring the concentration of metal in the tree ring. Full article