PUBLISHED BY THE EUROPEAN RESPIRATORY SOCIETY CHIEF EDITORS Ernst Eber (Graz, Austria) Fabio Midulla (Rome, Italy) ERS STAFF Caroline Ashford-Bentley, Alice Bartlett, Sarah Cleveland, Claire Marchant, Catherine Pumphrey, Elin Reeves, Ben Watson © 2021 European Respiratory Society Design by Claire Marchant, ERS Typeset by Nova Techset Private Limited, India Indexed by Merrall-Ross International, UK Printed by Page Bros Group Ltd, Norwich, UK All material is copyright to the European Respiratory Society. It may not be reproduced in any way including electronically without the express permission of the society. CONTACT, PERMISSIONS AND SALES REQUESTS: European Respiratory Society, 442 Glossop Road, Sheffield, S10 2PX, UK Tel: +44 114 2672860 Fax: +44 114 2665064 e-mail: books@ersnet.org Print ISBN: 978-1-84984-130-6 Online ISBN: 978-1-84984-131-3 ePub ISBN: 978-1-84984-132-0