1. Department of Respiratory Medicine, Government Medical College Bhavnagar, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar, India
2. Department of Community Medicine, Government Medical College Bhavnagar, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar, India
3. Department of Clinical Epidemiology, Division of Health Sciences, ICMR-National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Ahmedabad, India