Non-invasive assessment of pollutant particles in the lower airway of children and adults

Epidemiological studies in children suggest that inhalation of carbonaceous particulate matter (PM) adversely affects children's respiratory health. However, the relationship between markers of PM exposure and the quantity of particles entering the paediatric airway is unclear. The hypothesis was that, the carbon in alveolar macrophages (AM) reflects individual exposure of healthy children to PM. The aim was to quantify carbon in AM in extreme (biomass smoke) and with fossil fuel exposure. For fossil fuel exposure the aim was also to establish the relationship between median carbon loading per AM per child and: i) markers of exposures at the home address and ii) lung function iii) markers of airway inflammation. Healthy children were recruited from schools. Exercise parameters recorded. Environmental smoke exposure was excluded by salivary cotinine. AM were sampled by induced sputum. Median carbon area was determined by image analysis of digitized light microscopic images of AM. The median area of AM carbon was higher in Ethiopian women compared with UK adults, (p = 0.0002). Median carbon area in Ethiopian children was higher than UK children (p = 0.0002). In fossil-fuel exposure group, a weak, but significantly positive, association was found between median carbon area and modelled primary PM10 (p = 0.022), and a stronger inverse association between median carbon area and FEV1% predicted (p = 0.004), and FEF25-75% predicted (p = 0.004). There was no significant association between median carbon area and exercise variables and markers of airway inflammation.