Comparing the environmental pollution of transportation systems, the total pollution of the systems must be corrected for the extent the systems are used by travellers. It is usual to do this by dividing the pollution by the number of person kilometers. However, a problem of using the person kilometer as a `unit of use' of transportation systems is, that this unit is dependent on the quality of the transportation systems itself, in particular their speed. An alternative unit that also corrects for differences in use of transportation systems and to which the problem mentioned does not apply, is the person minute. This might be a better unit to correct the pollution of transportation systems for the extent they are used. If one replaces the person kilometer by the person minute, the ranking of the transportation systems relating to their pollution will not change much. However, the differences between systems with a low and a high pollution level become larger. The cleanest of the motorized systems are the bus and rail systems, the most polluting are the car and the airplane. Using the person minute as the correcting unit, the airplane is even much more polluting than the car. (A)
Samenvatting