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Air_pollution_main report_WEB

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Chapter 4: Health effects of air pollution over our lifetime In the previous chapter, we reviewed the reasons why the fetus and the child are especially vulnerable to air pollution, and why this vulnerability has implications for health across the lifecourse. This chapter reviews the evidence that long-term exposure to air pollution has adverse effects on health in infants, children, young people and adults. In reviewing the evidence, we focus mainly on new-onset (incident) disease and, therefore, greater weight is placed on evidence from studies where large groups of individuals have been followed over long periods of time. 4.1 The growing and the ageing lung Maximising lung growth during childhood and minimising lung function decline during ageing are important because the development of low lung function (measured by spirometry as FEV 1 and FVC) means that there is less reserve if lung disease develops. For example, in asthmatic children, low lung function detected by spirometry predisposes to more severe asthma symptoms and decreased quality of life. In healthy young adults in the Coronary Artery Risk Development in Young Adults (CARDIA) study, accelerated decline in lung function over a 10-year period was associated with lower output of blood from the heart, 1 and recent analyses of data from the Framingham Offspring Cohort, the Copenhagen City Heart Study and the Lovelace Smokers Cohort found that low FEV 1 in early adulthood predisposes to the development of COPD in later life. 2 A lung function of <80% of that expected is normally used as a cut-off to indicate an increased risk of respiratory symptoms. 4.1.1 Infants As discussed earlier, adverse effects of air pollution on the developing fetus may have long-term effects on lung development during extrauterine life. Separating the effects of exposure during gestation from the effects of exposure during infancy is difficult, because new mothers with infants usually live at the same address as when they were pregnant. However, a recent study reported an effect of fetal exposure per se on lung function in later life. In this study, increased exposure to NO 2 during the second trimester of gestation was independently associated with reduced FEV 1 measured at 4.5 years of age. 3 4.1.2 Schoolchildren In schoolchildren, the effects of air pollution over time on the increase of FEV 1 and FVC (as indices of lung function growth) have been examined in the Children's Health Study. This study recruited more than 11,000 schoolchildren selected from classrooms in 16 communities in California, USA. 4 Children were chosen from different areas to reflect the widest range of background regional pollution, which is the component of air pollution that all children are exposed to within a community. Lung function was measured every year and long-term background levels of air pollution were measured using monitoring stations in each community. After adjusting for a wide range of confounding variables, suppression of lung function growth was found in children living in communities with the highest concentrations of PM 10 , PM 2.5 , elemental carbon and NO 2 (Fig 11). 52 © Royal College of Physicians 2016

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