The patient comes to the doctor, and the doctor takes a complete medical history the finding follow: A 24-year-old male auto body shop worker with a 4-year history of slowly progressive respiratory complaints which include shortness of breath, chest tightness, wheeze, cough producing minimal white phlegm. The past medical history shows no history of childhood asthma. He is a smoker with no history of substance abuse. He started working in the auto body shop roughly 4 ½ years ago, at which time he was symptom-free. He is exposed to polyurethane paint fumes, asbestos and other chemical fumes at his job. No seasonal symptoms or home precipitants are reported. The physical examination shows no problems with the nasal passages or the airways. Chest x-rays and lung function test were ordered. Chest x-rays showed nothing abnormal. Lung function tests did indicate lower respiratory tract involvement. Based on the reading, what is your diagnosis? How would you treat this patient? Provide evidence and rational for your decisions.