This article focuses on the two important factors that contribute to differences in the estimated external costs. We report the sensitivity analysis in the external cost estimates with alternative specification for emissions factors specified in available databases and monetary values for CO2 and human health damages.
To illustrate the importance of knowing the exact data quality and assumptions used, the calculation of external costs for different transport technologies (passenger car, light duty vehicles, heavy duty vehicles, urban buses) and fuels (gasoline, diesel, LPG, CNG) are based on the same concept with air dispersion modules and dose-response functions. Although the methodology is the same, except for data on emission factors and monetary values of human health impacts, the estimated external costs differs by two to five orders of magnitude according to specific technology and region.