Oral food challenge (OFC) remains the gold standard for the diagnosis of food allergies. However, this test is not without risks, given that severe allergic reactions can be triggered while it is conducted. The purpose of this study is to identify potential demographic variables, clinical characteristics of the patients and biomarkers that may be associated with severe reactions during the hazelnut oral challenge test. The sample included 22 children allergic to hazelnut who underwent a tree nut skin prick test (SPT), specific IgE (sIgE) to hazelnut, component-resolved diagnosis (CRD) with different hazelnut allergens (Cor a 1, Cor a 8, Cor a 9, Cor a 11, Cor a 14), and a single-blind placebo-controlled challenge with hazelnut. A statistically significant relationship was found between the severity of the reaction and the highest values of sIgE to hazelnut, Cor a 11 and Cor a 14, cumulative symptom-triggering dose and sunflower seed sensitization. The use of the CRD is a useful tool to identify patients at higher risk of developing a severe reaction. In this pediatric population sample from Spain, storage proteins were confirmed to be most involved in hazelnut allergy and the development of severe reactions.

Tree pollen is the most abundant in the Community of Madrid (CAM), and specifically, pollen types from Olea, Cupressaceae, and Platanus are the most allergenic, after Gramineae, in this Spanish region. Air pollutants are one of the most significant stress factors for wind-pollinated vegetation, especially in urban areas, and can cause alterations in the immune system and the consequent triggering of type I hypersensitivity reactions mediated by immunoglobulin E (IgE). This study analyses the allergic sensitization caused by the interrelation of O₃, NO₂, and PM₁₀ pollutants with the tree pollen types Olea, Cupressaceae, and Platanus in the period 2017–2021. To this end, general linear models were calculated using the Statgraphics Centurion 19 tool. The data collected came from the Air Quality Networks of the CAM and Madrid City Council, the CAM Palynological Network, and the Allergy Services of the reference hospitals in the five study areas. This research confirms a statistically significant correlation between allergic sensitivity to pollen types and their concentrations in the air, and those of atmospheric pollutants, in the different areas and years studied. These pollen and pollutant concentrations in the atmosphere of the CAM jointly influence the prevalence of allergic sensitisation, as is evident in all the models calculated.