Modelling studies suggest that urban cycling is associated with an increased inhaled dose of fossil fuel-derived black carbon (BC). Using the amount of black material in airway macrophages as a marker of long-term inhaled BC, we sought to compare inhaled BC dose in London (UK) cyclists and non-cyclists.Airway macrophage carbon was assessed in 28 (58%) out of 48 healthy adults (14 cyclists and 14 non-cyclists) who attended for induced sputum. Short-term (24 h) exposure to BC was assessed on a representative working day in 27 out of 28 subjects. Serum interleukin (IL)-1b, IL-2, IL-6, IL-8, granulocyte-macrophage colony-stimulating factor and tumour necrosis factor (TNF)-a were assessed in 26 out of the 28 subjects.Cyclists were found to have increased airway macrophage carbon when compared with noncyclists (mean¡SE 1.81¡0.21 versus 1.11¡0.07 mm 2 ; p,0.01). Short-term monitoring showed no difference in 24 h BC exposure between the two groups. However, cyclists were exposed to higher concentrations of BC during commuting (p,0.01). Airway macrophage carbon was associated with monitored commute BC (n528; r50.47, p,0.05). TNF-a was found to be increased in cyclists (p,0.05), but no other cytokines were increased. Commuting to work by bicycle in London is associated with increased long-term inhaled dose of BC. Whether cycling per se increases inhaled BC dose remains unclear.

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