Ronald Dahl is a global medical expert for GSK. He previously worked as Professor of Respiratory Diseases at Aarhus University, Denmark and as Professor at the Allergy Centre, at Odense University Hospital and University of Southern Denmark, and now is adjungated professor at these institutions. His main research was initially related to the functions of the eosinophil granulocyte in allergic diseases and asthma, which led to clinical and pharmacological investigations of inhaled corticosteroids in asthma. These studies were pivotal to establish inhaled corticosteroid as the primary and prophylactic treatment for asthma. Further developments were done in relation to diagnoses and treatment of obstructive lung diseases with studies on long and ultra-long acting beta-agonists and ultra-long acting anticholinergic drugs in COPD and asthma. Other areas of research has been related to smoking cessation, the concept of “united airways”, indoor air quality, house dust mite allergy and studies on allergen immunotherapy for rhinitis and asthma as SCIT and SLIT and.