Preface R esearch within in the field of airway and lung inflammation has expanded tremendously during recent decades. Attempts are continuously being made to find novel methods to mirror and monitor inflammatory reactions related to airway disorders and dysfunction. The lungs are particularly well suited for this purpose as we have easy access to exhaled air and thereby a possibility to develop methods that measure compounds directly released from them. As this area of interest is rather new this is the first issue of the European Respiratory Monograph to focus on inflammatory markers. As this field is rapidly expanding it was decided, after some initial discussions, to limit this Monograph to markers in exhaled air and to produce a comprehensive update of the entire field. The Guest Editors have succeeded in attracting leading experts within the field to author the chapters. Five chapters have been devoted to different aspects of nitric oxide measurement. Carbon monoxide and volatile organic compounds in exhaled air have been thoroughly reviewed as has the assessment of exhaled breath condensates, which is probably the most expansive area within the field. The Guest Editors are to be congratulated for this excellent Monograph, which fills the need for a comprehensive review of this very important field. I am convinced that both scientists and clinicians will repeatedly use this Monograph and find it useful in their daily practice. Editor in Chief K. Larsson Eur Respir Mon 2010. 49, vi. Printed in UK – all rights reserved, Copyright ERS 2010. European Respiratory Monograph ISSN: 1025-448x. DOI: 10.1183/1025448x.00019710 vi