This is an 18-month research project funded by New Zealand Transport Agency, developing two core models for assessing the exposure of populations to air pollution arising from vehicle tailpipe emissions.

The Problem

Research has highlighted that time spent in close proximity to transport emissions, especially during travel, is a major cause of illness, with a burden on society as great as that from road traffic accidents. Beyond implementing vehicle emission standards, much of this burden can be reduced by targeting policies and schemes where exposure is greatest and by adopting exposure-reduction as an indicator of sustainable transport policy.

Currently, impacts of transport emissions are judged in terms of total emissions, with little or no regard for how the burden on health is shared amongst the population. This research is designed to permit transport schemes and policies, and the options they present, to be compared in terms of how they improve or worsen those impacts and how those impacts are distributed.

Contact details

Programme Leader: Ian Longley, ph: 09 375 2096, fax. 09 375 2051, i.longley@niwa.co.nz

The Solution

The project consists of two components, representing the current needs of operational users, and the needs of the research community in anticipation of the future needs of operational users.
Those two components comprise the development of two key modelling tools:

1. A road-corridor air quality model predicting local deterioration in air quality on a long-term basis in a corridor of up to approximately 300 m either side of major roads. 
2. A vehicle ventilation model predicting exposure of vehicle occupants to tailpipe emissions as a function of route and vehicle parameters.

Progress

Road Corridor Air Quality Model

• A draft model has been developed and currently exists in spreadsheet form. It is currently being internally reviewed and documented.
• The model predicts long-term average enhancements in concentrations of PM10, CO, NOx and VOCs on either side of any major road for which traffic data is available.
• Traffic data required is Annual Average Daily Traffic, and estimates of average speed and fleet composition. If AM, PM or inter-peak volumes can be provided, then air quality impacts can be estimated for these corresponding periods only.
• We have investigated the potential for hosting this model in a GIS-based environment. We have concluded that this is the desired future format. This aspect will be progressed by NIWA in 2010 outside of the scope of this Project.
• The model will be extensively validated and compared with existing and alternative models by NIWA within the NZTA-funded Project TAR 09/18 (2010-2012).

Vehicle Ventilation Model

• This model has been developed from scratch, based on observational data captured by NIWA in busy Auckland traffic.
• The model successfully predicts concentrations of CO and particles within cars on a second-by-second basis, based on a profile of external concentrations.
• Initial results were presented at the Australia & New Zealand Aerosol Seminar, hosted by NIWA in Auckland in July 2009.
• Extensive data is currently being collected through the WAIVE study (Waitakere to Auckland In-Vehicle Exposure).
• We are currently investigating the prediction of the external concentration profile based upon combining observational data of traffic and traffic and emission modelling.