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Miljøzoner, partikler og sundhed

Summary and conclusions

The Danish Environmental Protection Agency (DEPA) and the Danish Road Safety and Transport Agency work together in investigating possibilities to reduce particle emissions from diesel vehicles to reduce the environmental damage. A technical solution to the problem is to install vehicles with particle filters. That is a filter that intercepts a large proportion of the particles of all sizes from vehicle exhaustion gas.

Objective

Emissions of particles are associated with adverse health effects and cause the greatest damage in cities where most people live and work. Therefore DEPA wishes to investigate the possibility to implement initiatives to reduce the concentration of particles in Danish cities.

The project objective is to assess the overall consequences of implementing a law calling for obligatory use of particle filters for trucks and buses weighing more than 6 tonnes in environmental zones.

An Environmental Zone is defined as:

"A geographically bounded area in which certain restrictions for traffic applies in order to reduce the environmental impacts in the central urban areas"

The economic, environmental and health consequences is discussed for three specific case-cities for which accessible traffic data is collected and interviews with relevant players are conducted. On the basis of the case-studies and a national evaluation of the environmental and health benefits of installing the vehicles with particle filters an evaluation of the overall consequences of implementing environmental zones in the four and the ten biggest cities in Denmark respectively is undertaken.

The project output describes the financial and organisational consequences for transport operators as well as the overall economic and environmental effects for society.

Delimitations and critical assumptions

In the study, it is generally assumed that a particle filter reduces the emissions of particles from a vehicle by 80% of all fraction sizes. Further, it is generally assumed that a particle filter costs app. dkr. 60.0000.

The study has been limited to include only buses and trucks above 6 tonnes. This means that light duty vehicles are not included. The interviews were only conducted with commercial and private bus (tourist coach) companies while public bus companies where not included.

The environmental and health assessments are based on the results of a national study of the environmental and health consequences of installing all heavy duty vehicles with particle filters. This study was undertaken by the Danish Road Safety and Transport Agency, the National Environmental Research Institute (NERI), University of Copenhagen, Institute of Public Health by Prof. Steffen Loft and

Danish Cancer Society by Reserarcher Ole Raaschou-Nielsen.

Case Cities

The three case cities are Copenhagen, Aalborg and Vejle. For each of these three cities the environmental zone has been determined and described. The delineations have been made with respect to the population density and physical conditions.

Methodology and data basis

For each of the three case cities the traffic loads of trucks and buses in the zones have been estimated primarily on the basis of traffic data from the municipalities. The effects on traffic of the environmental zones have then been estimated from these estimates and the results of the interviews of relevant transport companies. The interviews included dialogue with haulage contractors, carriers, bus companies and companies with their own distribution.

The effects of introducing environmental zones are first analysed and estimated for the three cities separately. Subsequently the effects are estimated for an introduction of environmental zones in the four and ten largest cities based on the information from the case studies.

Conclusions

This project has proven that the consequences of implementing a regulation calling for obligatory use of particle filters are complex and it has shown that analysis of the consequences is difficult and associated with considerable uncertainty. As a consequence a true cost-benefit analysis, quantifying and weighing together all effects and taken into account the time factor, has not been undertaken. In the economic analysis the costs of installing the filters was merely compared with the health benefits from reduced exposure to particles. The pragmatic comparison shows that the costs are higher than the benefits, even when the costs are depreciated over as many years as the mean expected remaining life years of trucks.

The traffic analysis, primarily based on interviews studied the effects of different degrees of public co-financing of the particle filters. The analysis showed that the degree of public co-financing only have a very modest influence on the traffic intensity in and outside of the zone because the largest proportion of the transport contractors will install filters on all trucks to keep maximal flexibility. Only very few transport contractors believed that they would be able to optimise the planning procedure and thereby avoiding to install filters on all vehicles.

The health consequences have been analysed on the basis of a methodology outlined by the WHO. On this basis the reductions in fatalities and mortality and the associated benefits measured in monetary values have been estimated to a relatively modest level. If particle filters were installed on all heavy vehicles, Denmark would reduce the number of premature deaths by app. 22 per year, which should be compared to the total potential of 5000 premature deaths. Hence a reduction of only 0,4% of the total premature deaths. If particle filters were only installed on all heavy vehicles in the 4 largest cities, the number of premature deaths would be reduced by 5 per year.

The latest science indicates that it is mostly the number of ultra fine particles that contributes to adverse health effects. Therefore the above analysis probably underestimates the health benefits from the particle filters.

The concentration of particles is highest in the large cities and the busiest streets where most people live and work and therefore the reduction of the ultra fine particle concentration and the health effect will probably be substantial in these areas.

Based on the WHO methodology the health benefits from introducing environmental zones in the four largest cities is estimated to 38 mill dkr (in 1996-dkr). These benefits should be compared to the costs of installing the particle filters which amount to 1130 mill dkr. Again, it should be noted that the health benefits are presumably considerably underestimated.

If the ultra fine particles are the real source of the adverse health effects the theoretic maximal potential reductions of deaths in the four largest cities amount to 350 per year (1/3 of 21% of 5000).

All in all an introduction of environmental zones in the largest cities in Denmark will only lead to a minor reduction of PM₁₀, but a substantial reduction of the ultra fine particles, which is presumed to have a significant influence to the adverse health effects. The results of the study should be treated with great care and is considered to be the first shot of estimated the effects since the study is based on uncertain and incomplete data.