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Cost and Benefit analysis for HM - AQ0813

The emissions of metals into the atmosphere can have adverse impacts on soil and freshwater organisms, as well as on the long-term sustainability of soils, and can affect human health through direct inhalation and through the food chain. Although European emissions of potentially toxic metals such as lead, cadmium, and mercury have decreased significantly over the past two decades, they may still exceed environmental thresholds for adverse effects on human health and on ecosystems. To minimise the risk of these adverse effects, there are ongoing discussions within the UN/ECE Convention on Long-range Trans-boundary Air Pollution (CLRTAP) of the need for, and benefit of, further measures to reduce emissions of potentially toxic metals to the atmosphere. These discussions should be informed by detailed evaluation of the feasibility, costs and benefits of these additional measures.

Any such further measures need to be justified on the basis of a full assessment of their environmental and health benefits. However, the assessment considered to date by the Task Force on Heavy Metals (TFHM), the body within the CLRTAP which is responsible for evaluating additional abatement measures, was primarily based on a detailed analysis of the costs and feasibility of a range of emissions control options. This is because it provides an assessment in terms of exceedance of critical loads, which are the rates of deposition from the atmosphere at which critical threshold concentrations in soils or waters (termed critical limits) will be reached. These critical loads are based on an assumption of steady-state, at which the rate of input of metals from the atmosphere is balanced by losses of metals (e.g. in water flows, through harvesting) from the ecosystem of concern.

However, recent research under a Defra contract has shown that the response of metal concentrations in soils and waters to changes in metal deposition from the atmosphere can be very slow, i.e. a timescale of decades or even centuries. This has major implications for policy assessment, since the many of the benefits of immediate further reductions in deposition of metals from the atmosphere will only be realised well into the future. It could be argued therefore the work plan of the TFHM, to properly ‘assess the quantitative and, where this was not possible, qualitative information on health and ecosystem benefits of further measures to reduce emissions of heavy metals’ has not been met if the assessment is only based on steady-state critical loads.

The aim of this project is to develop and apply new methods for assessing the environmental benefits of measures to reduce metal deposition that take into account the timescale of environmental responses. These will be designed for application by TFHM and other bodies within CLRTAP. Our approach will be based on the dynamic models that we have already developed and applied. We have used these models to predict changes in metal concentrations in soils and waters in upland areas of the UK in response to changes in metal deposition, but also to deposition of sulphur and nitrogen, and changes in organic matter, which can also significantly affect metal concentrations and their environmental impacts. In order to apply these models in a European context, we will select about twenty locations in different parts of Europe, with different climates, metal deposition, and soils and vegetation, and adapt the model parameters to predict changes in these different locations to the same reduction in metal deposition. This will provide important new information about the dynamics of change in different regions of the continent.

We will then develop a simple economic framework to value the different benefits over different timescales of changes in metal concentrations, considering effects on human health, soil function and sensitive organisms. This economic framework will be designed for consistency with work already done with CLRTAP and the EU to value the long-term benefits of measures to control emissions of pollutants.

Finally, we will identify a small number of emission control scenarios for more detailed analysis. These will be selected in close consultation with staff in Defra and will be designed to be directly relevant to options for control of metal emissions that are being considered by TFHM. The benefits of these different scenarios will be summarised and presented both orally and in a written report to the TFHM and other relevant bodies within the CLRTAP.
1. To carry out an initial scoping study to critically evaluate existing methods used to assess the benefits of reductions in heavy metal emissions.

2. To establish a dynamic modelling approach that can be applied for benefit analysis in different parts of Europe and to apply this to selected locations representative of generic ecological and geo-political regions.

3. To develop an economic framework for assessment of the benefits of changes in metal concentrations in air, soil and water.

4. To identify emission control measures and scenarios for detailed analysis

5. To undertake preliminary analysis of the benefits of a limited range of emission control scenarios

6. Based on feedback from (5), either modify key aspects of the analytical framework or undertake analysis of further emission control scenarios
Time-Scale and Cost
From: 2008

To: 2010

Cost: £123,665
Contractor / Funded Organisations
University - York
Air Pollution              
Environmental Protection              
Heavy Metals              
Fields of Study
Air Quality