Inhalable elemental black carbon (BC) from fossil fuel combustion impairs lung health. We recently developed a novel method for assessing internal dose of BC using the amount of BC phagocytosed by airway macrophages (AM). To date, the determinants of AM carbon in healthy individuals living in urban areas remain unclear. Personal external monitoring indirectly suggests that cyclists have high levels of BC exposure.Aim
To compare AM carbon in healthy adult cycling (cyclist) and non-cycling (pedestrian) London commuters.Methods
AM carbon was assessed in non-smoking urban commuters aged 18 to 40 yr. AM were sampled using sputum induction, imaged under light microscopy (x60) and the area of carbon in 50 random AM determined using image analysis (mean AM carbon, μg/m2
Cyclists and pedestrians had similar lung function and home-main road distance. Cyclists reported more weekly exercise but this difference did not reach significance (Table 1).
Table 1Demographics and Baseline Data
| ||Cyclists (mean, SEM)±||Pedestrians (mean, SEM)||P (t test)|
|Age (yr)||31.0 ± 2.4||24.8 ± 2.4||NS|
|Baseline FEV1 (% predicted)||99.2 ± 4.0||95.2 ± 3.2||NS|
|Distance of home from main road (km)||0.16 ± 0.0||0.18 ± 0.0||NS|
|Reported exercise (hr/week)||4.4 ± 1.5||1.6 ± 1.2||NS|
Cyclists had significantly more AM carbon than pedestrians (Chart 1).Conclusion
Cycling in London is associated with a higher internal dose of BC. These data suggest a need for low-pollution cycling routes.