Furthermore, the particular bus in which the commuter travelled during this week was not air conditioned so ventilation was provided by open windows, allowing air to flow freely in and out of the bus. This is an interesting result as it demonstrates that due to the high temporal and spatial variability in CO concentrations, other variables (such as ventilation rate and proximity to emissions) may be more important in determining exposure than choice of transport mode. For the runner, exposures were lower than for the car and bus commuters when running along the dedicated footpath/cycleway but not significantly lower.
