There were studies in the adult population to suggest FENO correlated with ACT scores [10, 11, 13, 14], blood eosinophil level [12], blood total IgE level [9], positive skin‐prick test, the presence of allergic rhinitis, the presence of allergic conjunctivitis, history of emergency room visits, and spirometry indicators of airway obstruction [13]. This evidence concerns the gene IGHE and Airway obstruction.