This is a prospective cross-sectional interventional design. 73 asthmatic patients who applied to Mersin University Faculty of Medicine Hospital Chest Diseases Clinic between 01.10.2019-01.04.2020 will be taken. 35 healthy volunteers who were admitted to our clinic within the same date range will be taken as control group. Impulse oscillometric pulmonary function tests will be performed to all participants. Thorax computed tomography will be performed to evaluate small airway dysfunction. To evaluate the degree of disease inflammation and phenotype in asthma patients, nitric oxide measurements will be made in the breath air with fractional exhaled nitric oxide (FENO) device. The blood eosinophil level will be studied to determine the asthma phenotype.Asthma control test (ACT) will be applied to measure symptom control in patients with asthma. Asthma quality of life scale (AQLQ) will be applied to determine the quality of life in asthmatic patients. All patients will be followed for 1 year to record the number of exacerbations requiring emergency and hospital admissions for asthma. The effect of small airway dysfunction on asthma group, on the disease severity and control degree, disease phenotypes and quality of life, and the effect on the risk of exacerbation will be analyzed.