Original Article [Received: October 29, 2008; accepted after revision: June 23, 2009] Correspondence and reprint requests: Dr Raj Kumar, Flat No. 7, Type IV, Patel Chest Flats, Maurice Nagar, Delhi University Campus, Delhi – 110 007, India; Phone: 91-11-27667667, Extn 144; Fax: 91-11-27666549, E-mail: rajkumar_27563@yahoo.co.in Breath Carbon Monoxide Concentration in Cigarette and Bidi Smokers in India Raj Kumar, Suraj Prakash, A.S. Kushwah and V.K. Vijayan Department of Respiratory Medicine, V.P. Chest Institute, University of Delhi, Delhi, India ABSTRACT Objective. To measure and compare the breath carbon monoxide (CO) levels in cigarette and bidi smokers in India. Methods. Breath CO was measured in 389 smokers (241 cigarette smokers,148 bidi smokers) using portable breath CO analyser (Bedfont-England, Smokelyzer). Tobacco contents and length of single stick of different brands of cigarette and bidi were also measured. Results. Their mean age was 38.7±13.4 years. The average duration of smoking was 18.2±13.0 years. Average breath CO levels were 15.6±7.0 ppm in smokers and 4.07±1.16 ppm in non-smokers. Average breath CO level was significantly higher in bidi smokers (18.9±7.7 ppm) compared to cigarette smokers (13.6±5.8 ppm) when total consumption of cigarette/bidi was more than five pack-years (p=0.002). Average tobacco weight of bidi (216.8mg) was significantly less than cigarette (696mg). Conclusions. Bidi is equally or more harmful than cigarette smoking. One bidi may be considered to one cigarette for calculating “pack-years” of smoking. [Indian J Chest Dis Allied Sci 2010;52:19-24] Key words: Carbon monoxide, Bidi, Cigarette, Pack-years. INTRODUCTION Smoking is prevalent all over the word. According to World Health Organization (WHO) estimates, there are around 1100 million smokers worldwide. This constitutes about one-third of global population aged over 15 years. 1 Deaths due to tobacco use accounts for around three million globally every year. 2 Tobacco smoke contains more than 4000 chemicals and around 40 carcinogens, including nicotine, tar, carbon monoxide (CO), methoprene, propylene glycol, benzopyrene, butane, cadmium, acetone, ammonia, lead, benzene, formaldehyde, etc. When inhaled, CO from tobacco smoke is absorbed through lungs and enters into the blood stream and combines with haemoglobin to form carboxy-haemoglobin (COHb), which can be measured in the blood and is a useful marker of tobacco smoke absorption. 3 The CO remains in the blood for about 24 hours after inhalation of tobacco smoke depending on various factors, such as gender, physical activity and ventilation rate. 4 The CO in the blood then re-enters the alveoli because of concentration gradient at the alveoli. The CO present in expired air can be measured using a portable CO analyser. The breath CO concentration has been found to be a reliable indicator of COHb level in the blood. 5 Therefore, indirect measurement of COHb through breath analysis is preferred over direct measurement of blood COHb levels because of its non-invasive nature, easy procedure and better compliance. 6 Smoking has been considered as a prime cause of CO exposure, though small amount of exposure can also occur due to vehicular smoke emission, occupational exposure among others. 4 However, a small amount of CO is also produced endogeneously as an end product of red blood corpuscles (RBCs) metabolism because of which raised levels are found in acute haemolysis and post-blood transfusion phase. 7 It has also been reported that breath CO levels can be raised due to various inflammatory lung diseases, like bronchiectasis, asthma, etc. 8 Some studies 9,10 have been done to correlate the number of cigarettes smoked per day and levels of CO in breath. However, not much studies have been done for “bidi smoking”, which is a very much prevalent form of smoking in India. Therefore, the present study was undertaken to measure breath CO concentration in bidi smokers and to compare it with the exhaled breath CO concentration in cigarette smokers.