Detailed observations and validated modelling of the impact of traffic on the air quality of roadside communities (original) (raw)

The research described in this report was designed to serve two key and related needs: 1 To assist in the enhancement and development of modelling tools to assess the local air quality impacts of road transport emissions 2 To provide data and models that will enable the development of New Zealand-based estimates of health effects of those impacts on local air quality. Recent international research shows that the air quality impact of major roads is significant up to a 250m distance and possibly further. Associated research reveals that a substantial health burden arises from the long-term chronic exposure to emissions in roadside communities, which is not represented by the national environmental standards for air quality (NES), and ignoring this burden, as is currently the norm, leads to an undervaluation of the resulting health-care costs attributable to traffic (Künzli et al 2008). A rational judgment of the cost-benefit of mitigation of traffic emission exposure requires that its full impact be quantified. However, before this project was carried out there was no New Zealand-based data while overseas data describes different emissions, climate and urban fabric. The objectives of this project were: 1 To conduct highly detailed observations of air quality in a typical New Zealand roadside residential community. 2 To generate a dataset suitable for the validation of roadside dispersion models, and use of that dataset to provide a validation of 1) the vehicle emission prediction model (VEPM) + Ausroads combination, 2) the National Institute of Water & Atmospheric Research (NIWA)/NZ Transport Agency (NZTA) roadside corridor model, 3) the semi-empirical site-optimised (SOSE) model, and 4) a land-use regression (LUR) model in a motorway setting. 3 To compare the performance of these four models and make recommendations on their use. 4 To enable and extend general health impact analysis of emissions from particular roads. We established a unique monitoring design that allowed the contribution of the road to local air quality to be estimated from the difference in concentrations between downwind and upwind sites. Our main study area was Otahuhu East in Auckland, a residential area bisected by the Auckland southern motorway (SH1). At this location the motorway carries 112,000 vehicles per day. This area was chosen for technical and logistical reasons rather than any pre-existing concerns about air quality or health outcomes there. An observational programme was conducted which comprised of three layers: 1 A unique dataset of monthly monitoring of nitrogen dioxide at 32 sites across the study area, and an additional 28 sites in the similar nearby community of Mangere, for a year (2010-11). 2 Intensive, partly-simultaneous continuous monitoring of particulate matter, oxides of nitrogen, ozone, carbon monoxide and meteorological parameters at a motorway kerbside site and two sites set back up to 250m either side of the motorway through autumn and winter 2010. 3 An additional campaign of 'mobile' particulate matter, carbon monoxide and black carbon using both a car and a bicycle on selected days in winter 2010. Four modelling evaluation studies were also conducted. These were: Detailed observations and validated modelling of the impact of traffic on the air quality of roadside communities 8 Detailed observations and validated modelling of the impact of traffic on the air quality of roadside communities 10