1. Respiratory Medicine, Centre for Workplace Health, University of Sheffield, Buxton, Derbyshire, UK and, Respiratory Physician, Royal Hallamshire Hospital, Sheffield, Health and Safety Laboratory, Harpur Hill, Buxton, Derbyshire, UK, ,
2. UK, and Respiratory Physician
3. Respiratory Medicine, Centre for Workplace Health, University of Sheffield, Buxton, Derbyshire, UK