Cigarette smoking is the dominant risk factor for the development of chronic obstructive pulmonary disease (COPD) [1,2], but only 10-15% of smokers develop the condition [1]. Several risk factors for COPD are known [2] but only apply to a small minority of cases. There is only a weak relationship between the lifetime number of cigarettes smoked and risk of COPD [2,3]. Smoke must be inhaled to damage the lung and it is the cumulative dose of smoke inhaled that would seem to be relevant to the development of lung injury. Smokers differ in the number and size of puffs taken per cigarette, depth and duration of inhalation, cigarette yield and size of discarded butt [4,5]. This study, therefore, investigated whether risk is more closely determined by aspects of smoking behaviour that affect the depth, duration and quantity of smoke inhalation.Indices of smoke inhalation were measured and related to productive cough, airflow obstruction and emphysema in smoking volunteers. These indices are boost of carbon monoxide (CO) in alveolar air after smoking one cigarette [6] and serum levels of the major primary metabolite of nicotine, cotinine [7]. Since lung damage may affect smoking behaviour or absorption of tobacco products smokers with a previously established diagnosis of COPD were not studied. Methods SubjectsEighty current cigarette smokers (Š5 cigarettes·day -1 ) aged 35-65 yrs (mean (SD) age 51 (7.7) yrs) (41 males and 39 females) and 20 lifetime nonsmoking controls (ð1 cigarette·day -1 for 1 yr) aged 50 (8.1) yrs (7 males and 13 females) were recruited after publicity in local media. All subjects were Caucasians. Exclusion criteria were a forced expiratory volume in one second (FEV1) <1.5 L, asthma, bronchodilator or corticosteroid medication and use of other tobacco products. All subjects who fulfilled the inclusion and exclusion criteria were included. The study was approved by the North Tees Local Research Ethics Committee and written consent obtained.Cumulative lifetime smoking was quantified as pack-yrs and the brand of cigarette smoked was recorded. Subjects completed a Medical Research Council (MRC) Respiratory Health Questionnaire. Blood was taken for measurements of serum α 1 -protease inhibitor (α 1 -antitrypsin) and haemoglobin concentrations.High-resolution computed tomography (HRCT) scanning was performed using an IGE Sytec 3000i CT scanner. Three 1 mm cuts from the upper, middle and lower Cigarette smoke inhalation and lung damage in smoking volunteers. K.D. Clark, N. Wardrobe-Wong, J.J. Elliott, P.T. Gill, N.P. Tait, P.D. Snashall. ERS Journals Ltd 1998. ABSTRACT: Cigarette smoking is the dominant risk factor for chronic obstructive pulmonary disease (COPD) but only 10-15% of smokers develop the condition. Risk does not relate closely to cumulative cigarette consumption, perhaps because smokers vary in the degree and depth of smoke inhalation. This study examined the role of smoke inhalation in the development of COPD.Eighty current smokers and 20 lifetime nonsmoking volunteers (aged 35-65 yrs) wer...