Identifying contributions of on-road motor vehicles to urban air pollution using travel demand model data

• Published in: Transportation research. Part D, Transport and environment Transport and environment, 2009-05, Vol.14 (3), p.168-179
• Main Authors: Wang, Guihua, Bai, Song, Ogden, Joan M.
• Format: Article
• Language: English
• Subjects: Air quality; On-road motor vehicles; Source contributions; Transportation pollution; Travel demand
• ISSN: 1361-9209; 1879-2340
• DOI: 10.1016/j.trd.2008.11.011

Ambient concentrations of pollutants are correlated with emissions, but the contribution to ambient air quality of on-road mobile sources is not necessarily equal to their contribution to regional emissions. This is true for several reasons such as the distribution of other pollution sources and regional topology, as well as meteorology. In this paper, using a dataset from a travel demand model for the Sacramento metropolitan area for 2005, regional vehicle emissions are disaggregated into hourly, gridded emission inventories, and transportation-related concentrations are estimated using an atmospheric dispersion model. Contributions of on-road motor vehicles to urban air pollution are then identified at a regional scale. The contributions to ambient concentrations are slightly higher than emission fractions that transportation accounts for in the region, reflecting that relative to other major pollution sources, mobile sources tend to have a close proximity to air quality monitors in urban areas. The contribution results indicate that the impact of mobile sources on PM 10 is not negligible, and mobile sources have a significant influence on both NO x and VOC pollution that subsequently results in secondary particulate matter and ozone formation.