1. Olfactory dysfunction prior to COVID-19 2. Clinical of chronic rhinitis or chronic rhinosinusitis 3. Intranasal tumor e.g. hemangioma, inverted papilloma 4. History of nasal or neurological surgery 5. Other current clinical of significant neurological disease 6. Current clinical of psychiatric disorders e.g. major depressive disorder 7. During receiving steroids form other conditions within 2 weeks 8. Pregnant 9. Major visual or auditory problem such as blindness or deafness which limit communication with the instructor

1. Olfactory dysfunction prior to COVID-19 2. Clinical of chronic rhinitis or chronic rhinosinusitis 3. Intranasal tumor e.g. hemangioma, inverted papilloma 4. History of nasal or neurological surgery 5. Other current clinical of significant neurological disease 6. Current clinical of psychiatric disorders e.g. major depressive disorder 7. During receiving steroids form other conditions within 2 weeks 8. Pregnant 9. Major visual or auditory problem such as blindness or deafness which limit communication with the instructor