Dispersion of particle numbers and elemental carbon from road traffic, a harbour and an airstrip in the Netherlands

Abstract

Emissions of combustion aerosol by transport activities near residential areas are associated with adverse health effects. The composition of combustion aerosol from road traffic, a harbour and an airstrip has been investigated by measurements of PM2.5, elemental carbon (EC), organic carbon (OC) and size-resolved particle number concentrations (PNC). PM2.5 concentrations are not significantly increased downwind of transport activities. Combustion aerosol from road traffic is identified by EC, OC and PNC and an airstrip by OC and a large number of nucleation particles (i.e. particles smaller than 25 nm). Combustion emissions from a harbour have not been distinguished from background concentrations probable due to the height of these emissions and their large temporal variability. EC is suggested (over OC and PNC) as an indicator for the mass of combustion emissions by road traffic. EC is more stable during dispersion, has a higher contrast against background concentrations and is relatively easy to monitor. From our study on size-resolved PNC downwind of a motorway, it is concluded that dispersion of PNC from road traffic may be modelled as a conservative parameter on a medium city scale. The modelled spatial distribution of EC and PNC in the city of Rotterdam shows that EC is elevated both near urban and motorway traffic, while PNC has the highest relative values near motorway traffic. This illustrates that the urban population is exposed to different levels and composition of combustion aerosol which may result in different health impacts.