Estimating the effectiveness of a vehicle miles travelled tax in reducing particulate matter emissions

This study estimates the effectiveness of a vehicle miles travelled (VMT) tax in controlling mobile-source emissions of particulate matter (PM2.5) in a non-attainment area located in northern Utah. Using a recently updated household-level dataset, the study finds no evidence of an endogenous relationship between choice of vehicle type and VMT. VMT elasticities are also estimated with respect to cost per mile that are in some cases larger in magnitude than those reported in previous studies. Based on vehicle emissions tests performed by the Houston Advanced Research Center, the study estimates the reduction in particulate emissions that would occur with two different sets of VMT tax rates. Principal findings are that a VMT tax rate of $0.003 per passenger car mile and $0.01 per light-duty truck mile (resulting in a mean annual tax burden of $128 per household in the first year) would reduce annual particulate emissions by between 7% and 11%, depending upon the degree of heterogeneity in household driving behaviour. Assuming constant elasticity, this means that at tax rates of $0.006 and $0.02 per mile for passenger cars and light-duty trucks, respectively (resulting in double the mean annual tax burden), annual particulate emissions would be reduced by between 12% and 23%. Both the advantages and limitations of the VMT tax are discussed.