International Symposium / Colloque International

Environment and Transport in different contexts

Environnement et Transports dans des contextes différents

Ghardaïa, Algeria / Algérie 27-28 Oct. 2008

ETGHAR’08

Abstract sample

Trends in air pollution impacts and external costs of passenger car traffic

Luis Karovski, Leonard Houghton, Paula Stenson*

Environmental Institute, Botalong Road 200, Greenbelt, MD 20772, USA

* Laboratoire de combustion, 4 rue Blaise Pascal, 67070 Strasbourg Cedex

Fax +1 420 388 11 39 – email luiskarovski@iees.org

Abstract

Objectives

Calculations of external costs provide a clear way of weighting different impacts and can therefore be used as a tool in policy related studies. In this paper we use external costs to look at changes in air pollution impacts between 1993 and 1998 and discuss how our view is affected by the use of different emission models.

Methodology

Our calculation of external costs is based on the accounting framework of the European ExternE project. Marginal impacts due to energy related pollutants are quantified using a detailed bottom-up approach. Impacts on human health and the environment are quantified by tracing pollutants from their source to their impacts. Different national or European databases of emission factors of road transport vehicles were used: COPERT, MEET, BUWAL/INFRAS.

Data on the fleet of passenger cars were derived from statistics kept by the federal national statistics institute and from the government agency responsible for the registry of vehicles.

Data on mobility (mileage, fuel and age) were derived from a large number of different expert assessments.

Results and Discussion

The air pollution caused by Euro 0 petrol cars was dominated by the health impacts of nitrate aerosols. The introduction of three-way catalysts, needed to comply with Euro1 emissions standards, has significantly cut the emissions of NOx and VOC. The reduction in externalities of diesel cars was mainly accomplished by the reduction PM emissions. The resulting decrease of PM impacts explains most of the reduction between Euro0 and Euro2 diesel cars.

Major reductions in CO emissions, although spectacular in terms of tailpipe concentrations, hardly affected the total external air pollution cost. The general effect of emission reductions implemented between 1990 and 1997 has been such that the damages caused by modern petrol cars are no longer dominated by local and regional health effects, but by the global effects of greenhouse gasses. Also in diesel cars, the relative importance of greenhouse gas impacts has increased. The refinement of estimates of global warming impacts has therefore become crucial for the precise estimation of external costs.

Conclusions

The external costs per vehicle.kilometre are significant and can exceed the private fuel costs (e.g. in urban traffic). They are dominated by public health impacts from primary (PM) and secondary particles (nitrates and sulphates) and by greenhouse gas impacts. This will allow a targeted improvement of precision, which is necessary to monitor and evaluate the evolution of exhaust impacts.

Key-words: external costs, air pollution, time-series, passenger car fleet, mobility