Summary, Miljøstyrelsen

Metoder til værdisætning af dansk vejtrafiks forurening af jord og grundvand

Summary

The cost of emissions into the soil and groundwater from road transport are normally not taken into account in social cost-benefit analyses. However, cost-benefit analysis is increasingly used as the basis for important policy decisions and it is therefore important that the methods and unit prices included in the framework are as complete as possible.

In this project the possibilities for valuation of emissions into the soil and groundwater from road traffic are assessed. Overviews of the characteristics of the pollution, the types of damage to humans and the environment from the pollution, and the methods of valuation are presented in the project.

This pre-project has been undertaken by COWI and financed by the Danish Environmental Protection Agency's technology fund for soil and groundwater.

The aim of this project is to provide a first overview of the problem and the current state of knowledge. It is a relatively small project and it is envisaged that the project will be followed by a larger project, which should aim to undertake an actual valuation of the emissions into the soil and groundwater from road traffic in Denmark.

Five main sources of pollution of soil and groundwater from the road traffic have been identified:

Single sources (petrol stations, garages)

Road traffic (such as exhaust gases, tyre-wear, road-wear)

Construction and maintenance of roads in general (asphalt coating, base (cinders, tar)) and levels below

Prevention of slippery roads (sprinkling with salt, sweeping etc.)

Weed control (pesticides, gas burning)

Other sources can also contribute to pollution along the road network, for example particles from industrial chimneys, etc. Hence, it is important to distinguish between pollution from road traffic and pollution from other sources.

The most important road traffic emissions/emission groups to soil and groundwater include:

MTBE

The heavy metal lead (Pb) (from petrol)

Total PAH, including benzo(a)pyrene

BTEX

Total hydrocarbons for the fractions C₆-C₁₀, C₁₀-C₂₅ and C₂₅-C₃₅

The heavy metals Cd, Cr, Cu, Ni, Zn and Pb

Chloride (in NaCl)

Pesticides

Phthalates.

Some of the above substances are no longer emitted, or they are currently being phased out, while others are still being emitted. Thus, lead in petrol has been phased out and pesticides are no longer being used for weed control. Furthermore, currently negotiations are taking place nationally as well as internationally to phase out MTBE. Even though no new emissions are being emitted into the soil and groundwater, the existing pollution can still cause damage to humans and the environment. Valuations of this damage are therefore relevant for both historical and future emissions. If pollution consists of historic emissions only, then of course there is no need to regulate demand, and no costs should be added to the price to internalise social costs. However, the social costs are still relevant for evaluating whether to clean or remove the polluted soil or to reduce the impacts from the pollution.

The above emissions can lead to damage to the health of humans and animals, failure of the crops, deterioration of biodiversity and deterioration of the quality of soil and water. It is assessed that the most important damage is to human health and deterioration of the groundwater. For example, emissions can affect the capability of reproduction, the central nervous system, and the immune system, as well as raise the risk of cancer and irritation. The damage and deterioration of the groundwater include deterioration in the taste of drinking water from MTBE and salt, which ultimately can make the water unsuitable for drinking.

As for methods of valuation, in principle the following methods, based on economic welfare theory exist:

Market valuation of physical effects
(existing market prices for effects/damage)

Direct methods
(interview-based surveys of individual willingness to pay)

Indirect valuation
(based on the correlation of the external effects with a marketed good)

The above methods are based on economic welfare theory and are therefore most appropriate because they base estimations on the demand curve for the effect. Besides these methods, a number of approximate valuation techniques exits. For example the Avoidance costs and Clean-up costs techniques. These techniques, however, do not base estimations on the demand curve. Finally, the so-called Benefits Transfer approach is often used for valuation. Benefits Transfer applies a data set (valuation) developed for one particular use to another context (such as using estimates from other countries).

The various valuation methods are appropriate for different kinds of impacts. Below the valuation method appropriate for particular damage categories is pointed out. Only the methods based on the demand curve are mentioned.

The appropriate valuation methods for various damage categories

Damage category	Appropriate valuation method
Reduced productivity	The market based method Avertive behaviour Defensive expenditure
Damage to health	The market based method (based on the Human Capital approach) Contingent valuation
Deteriorated amenity	Travel costs Hedonic pricing Contingent valuation
Loss of existence values	Contingent valuation

The project has shown that the valuation of soil and groundwater pollution from road traffic is very complex, and it has been documented that on central points the information needed to do the valuation is lacking. A complete valuation of all damage from emissions to soil and groundwater from road traffic is therefore not possible at the present time. Therefore, to a start, valuation will have to be limited to valuation of the most prominent and dominant damage (or substances) or to valuation of the damage from one or a few sources of pollution.

The project has shown that the level of information regarding potential sources of pollution to soil and groundwater as well as the types of substances and emissions are relatively good. Furthermore, the potential types of damage from exposure to the substances are well known. However, the quantitative scientific relationships between emission and exposure and exposure and damage have been very poorly described.

As for valuation, today no overall estimates exist. However, relatively well-developed methods for valuation are available just as estimates for certain specific effects and damage exist, such as value of life or lost productivity.

The conclusions regarding the level of knowledge about pollution of soil and water from road traffic have been summarised in the table below.

Available knowledge

	Good	Partly described	Poor
Sources of pollution	X
Types of emissions and substances	X
The quantities emitted			X
Spreading		X
Exposure			X
Types of damages	X
Level of damage			X
Valuation		X

A valuation project should therefore be limited to one or few polluting substances of particular interest. There seems to be a need for better knowledge regarding the quantitative scientific relationships between emission and exposure and exposure and damage. When this information is available, the appropriate valuation method for each damage category can be pointed out. The need for information for each valuation will depend on the method chosen. Thus, the market-based method calls for information about market prices, while the contingent valuation method involves undertaking a survey.

Since the pollution consists of many substances with very different effects, it may be difficult to limit the analysis. If the analysis of specific substances shows significant costs, then the cost estimate may be used as a minimum estimate in social cost-benefit analyses. However, if the analyses shows insignificant costs, then it cannot be concluded that the costs associated with pollution from traffic into the soil and groundwater are low, because other substances not yet analysed may have significant costs or because the combined effect of a number of substances could turn out to be significant.

For future work on the topic, developments in relevant on-going projects such as the EU POLMIT project about soil and groundwater pollution from road traffic should be followed closely.