A young runner with history of seasonal running nose, complains of sudden onset dyspnea early morning that improved after 2-3 hours. He has history of similar episodes in the past.on examination, patient is tachypneic, diffuse polyphonic expiatory wheeze heard on auscultation of chest, His x-ray is  normal. All except one is true regarding the clinical scenario.
Diffusion Lung capacity for carbon monoxide is Normal FEV1% is decreased Necrosis of airways Microvascular leakage resulting in airway edema.and plasma exudation into airway lumen