Cigarette smoking, indoor pollution and obstructive lung disease

Smoking is the most important risk factor for chronic obstructive pulmonary disease (COPD). Indoor pollution, especially the exposure to environmental tobacco smoke (ETS), has been considered important in recent years, since most time is spent 'indoors'. Quantitative relationships between cigarette exposure, respiratory symptoms and lung function have been documented cross-sectionally and longitudinally. The role of tobacco smoke on bronchial reactivity is still debated. Our epidemiological study shows that, after adjusting for initial airway calibre, only female smokers have higher values of bronchial reactivity. The relationships between responsiveness and longitudinal lung function change in forced expiratory volume in one second (ΔFEV1) are more complex, because of the strict dependence both of ΔFEV1 and bronchial reactivity on the initial level of lung function. Our data show that in subjects with chronic cough or phlegm the presence of bronchial reactivity affects ΔFEV1, at young ages (during growth) and in adulthood (during ageing). ETS is considered a risk factor to develop respiratory infections in childhood. Early respiratory events have been documented to be a risk factor for developing COPD in adulthood. Hence, ETS may also be hypothesized to play a role in the development of COPD, even if confirmation from longitudinal studies is still needed. In our population, increased prevalence of respiratory symptoms is present in houses where bottled gas is used for cooking.