Particulate matter exposure in children: relevance to chronic obstructive pulmonary disease

The effect of exposure to air pollution during childhood on the development of lung disease in adulthood remains to be defined. A common component of air pollution from fossil fuels, environmental tobacco smoke, and burning of solid fuels such as biomass is particulate matter (PM) less than 10 mum in aerodynamic diameter (PM(10)) consisting of aggregates of carbon spherules less than 10 nanometers. Epidemiologic studies suggest that the normal growth in lung function during childhood is impaired by long-term inhalation of carbonaceous PM(10). The most convincing evidence for an effect of PM on lung growth is from a longitudinal study performed in Southern California, where the majority of ambient PM is derived from fossil fuels. Whether exposure of children to high levels of PM from biomass fuel combustion also impairs lung function growth remains unclear. A direct link between exposure of children to PM and increased vulnerability to respiratory disease in adulthood is provided by studies showing an association between life-long biomass smoke and the development of chronic obstructive pulmonary disease (COPD) in non-cigarette-smoking women. Since carbonaceous PM is a component of mainstream cigarette smoke, there may be significant overlap in the cellular and molecular mechanisms underlying the adverse health effects of PM in children and the development of COPD in adult smokers. Studies of children, especially in the developing world, will therefore provide insights into the pathogenesis of COPD.