Issue link: https://hi.iaq.net/i/670243
Every breath we take: the lifelong impact of air pollution suppression of growth of lung function (measured as FEV 1 ) over an 8-year period, compared with children living >1,500 m from a heavily used road. The association between air pollution and impaired lung function growth has also been observed in other populations. For example, in a study of Taiwanese children followed over a 2-year period, reduced lung function growth (as FEV 1 ) was strongly associated with increased exposure to PM 2.5 . 6 More direct evidence that air pollution causes suppression of lung function growth is provided by a cross-sectional study of healthy schoolchildren in Leicester, UK. 7 This study used the capacity of macrophages resident on the mucosal surface of the lower airways to take up inhaled material, including pollution particles (PM) (Fig 12). In this study, each 1 µm 2 increase in the area of macrophage black carbon was associated with a 17% reduction in the expected FEV 1 (Fig 13). The question of whether reducing the levels of air pollution improves lung function growth was recently addressed. In its most recent analysis, the Children's Health Study found that declining levels of NO 2 and PM were associated with improvements in lung function growth. 8 Improved lung function growth, as a consequence of improved air quality, reduced the proportion of young people with an FEV 1 <80% of normal from 7.9% to 3.6%. In the UK, 7.9% of the population of 18-year-olds translates to approximately 58,500 individuals. Whether exposure to O 3 (a predominantly summer pollutant produced in the atmosphere by photochemical oxidation of primary pollutants on sunny days) reduces lung function growth is unclear. However, an effect of O 3 on 2-year lung growth was found in the Taiwanese study referred to above, 6 and a study of students who were lifelong residents of the Los Angeles and San Francisco Bay areas found that those with the highest exposure to O 3 had reduced measures of small airways lung function. 9 4.1.3 Adults As pointed out earlier, lung function in adulthood slowly declines with age. A recent analysis linked the long-term lung function of the US adults recruited into the Framingham Offspring or Third Generation studies with exposure in the home to air pollution, expressed as either distance of home from a major road or as modelled exposure to PM 2.5 . 10 This study found that adults living <100 m from a major road had a greater decline in FEV 1 than those living >400 m from a major road. In a study of older US men 54 © Royal College of Physicians 2016 Fig 12. Examples of macrophages recovered from the lower airways of healthy children living in Leicester. The black spots in some of the cells are inhaled fossil fuel-derived particles.