Healthy children’s sputum – a marker of exposure to air pollution at school?

<b>Background:</b> Airway macrophage black carbon (AMBC) provides an internal “dose” of pollution exposure as it is a reflection of how much they actually inhale. We previously reported in older school children (mean age 11.5y) an inverse association between AMBC and both FEV1 and FVC [1]. In a study of airway dendritic cells, we had the opportunity to assess whether this association was present in younger children. <b>Methods:</b> After informed consent, healthy children were recruited from schools and inhaled sputum samples were analysed for AMBC using light microscopy [1]. Pollution exposure assessment was modelled exposure at the home and school address using the London Air Quality Toolkit (12 months). Demographic data and spirometry was also done. Correlations were done by Spearmans Rank. <b>Results:</b> 148 children’s sputum samples were analysed for AMBC aged 8-14 years. There was a weak correlation between AMBC and 12 month modelled exposure at the school address (rs=0.171, p&lt;0.05) but not the home address (rs=0.086, p=0.35). There was an inverse correlation between AMBC and FVC z-score (rs= -0.173, p&lt;0.05). The correlation between AMBC and FEV1, was not significant (rs= -0.12, p=0.147). <b>Conclusions:</b> We confirm that AMBS is inversely associated with lung function. However this correlation is weaker than observed in older children previously. We speculate that this is because the cumulative effect of air pollution is still evolving. Our data also suggest exposure at the school is important and should be a focus of reduction strategies. 1. Kulkarni et al. Carbon in Airway Macrophages and Lung Function in ChildrenN Engl J Med 2006; 355:21-30