This is a multi-center study to explore the positive predictive value of bronchodilation test with portable oscillometry compared to either BDT or BPT with spirometry in asthma diagnosis and to compare it with bronchodilation with spirometry (the current gold standard). In the study, the target patients' profile is the suspected asthma patient with asthmatic symptoms (wheezing, shortness of breath, chest tightness, and/or cough) and aim to enroll 500 participants from 25 sites across different regions in China.