Pollution Reduction
Walking and bicycling produce no air pollution. Per mile emission reductions are large
because they usually replace short, cold-start trips for which internal combustion engines
have high emission rates, so each 1% of automobile travel replaced by walking or cycling
decreases motor vehicle emissions by 2% to 4% (Komanoff and Roelofs, 1993).
Estimated Benefits: Automobile air pollution costs are estimated to average 1¢ to 12¢ per
automobile mile, with relatively high values under congested urban conditions (Small and
Kazimi, 1995; McCubbin and Delucchi, 1996). Many monetized estimates include only a limited portion of total air pollution costs (for example, many ignore particulate pollution
and air toxics), so a relatively high value is appropriate. A conservative estimate is 10¢ per
mile for urban-peak driving, 5¢ for urban off-peak and 1¢ for rural driving.
SQW (2007) estimates that shifting from automobile to cycling provides air pollution
emission reductions valued at 11.1British Pence per car kilometre in major cities and Pence
in rural areas. 5.8 pence for petrol cars and and 32.2 pence for diesel cars in an urban area,
and 2.1 pence for petrol cars and 2.0 pence per kilometer for diesel cars in rural areas.
Table 5 summarizes these results.