where, Drm is the dose for route r of mode m in micrograms, m is
either walking or cycling, Li is the length (metres) of each link in the
route counted from i ¼ 1 to the total number of links n, Vm is the
velocity of mode m in metres per second, MVR is the minute
ventilation rate of mode m in metres cubed per minute, and Ci is the
air pollution concentration assigned to Li in micrograms per metre
cubed.