Modelling particle emissions from traffic flows at a freeway in Brisbane, Australia

The health risks of exposure to submicrometer particles (those with an aerodynamic diameter equal to or less than 1 μm) from vehicle exhaust, have led to a need to develop new models to predict likely levels of emissions from traffic flows. The lack of vehicle emissions factors for PM1 has been a limiting factor to-date. Researchers in Australia have been looking for a simple technique to predict levels of submicrometer particles contributed by traffic flows at the roadway. Work has focused on examining the relationship between submicrometer particle number concentrations and size distributions in relation to traffic volume, fleet composition, congestion, fuel usage and meteorological conditions. A technique has been developed to predict ambient submicrometer particle concentrations from traffic flows at a freeway site with up to 75% accuracy.