1. Lee Kong Chian School of Medicine and
2. Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
3. Department of Respiratory and Critical Care Medicine, Singapore General Hospital, Singapore, Singapore
4. Department of Respiratory and Critical Care Medicine, Tan Tock Seng Hospital, Singapore, Singapore; and
5. Department of Mathematics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, United Kingdom