When you smell the irritating odor, the lungs will be difficult to consider airway hyperreactivity, bronchial asthma and other reasons. 1. Airway hyperreactivity: its formation mechanism is very complex, a small number of patients with chronic bronchitis, and even some normal people, the airway excitation test can also show “airway hyperreactivity”, manifested as a very slight stimulus can induce changes in airway resistance, resulting in coughing, stuffiness and other discomforts. 2. Bronchial asthma: when inhaling irritating odors, cold air, pollen, etc., there will be a violent cough, chest tightness, breathlessness and other symptoms, but also need to consider the possibility of bronchial asthma. Its typical symptoms are episodes of expiratory dyspnea with rales, which can be accompanied by shortness of breath, chest tightness or cough, but some atypical asthma has no symptoms of wheezing, and only manifests itself as episodes of coughing, chest tightness or other symptoms. Smell the irritating odor lungs are difficult may also be other reasons, once the patient has symptoms of lungs are difficult, should immediately get out of the relevant environment, to avoid smelling the irritating odor again, serious need to immediately consult a doctor, under the guidance of the doctor treatment.