CAPÍTULO IV: METODOLOGÍA PARA EL DISEÑO DE DEPÓSITOS DE
4.5. Caracterización de materiales
4.5.2. Suelo de cimentación
As explained in paragraph 15 above, certain policies have been assessed using projected 184.
emissions data only, rather than full modelling of population weighted concentrations. The benefit associated with the emission changes between the measures and the baseline have then been valued using sector-specific cost per tonne estimates. These costs per tonne are described as damage costs.
The damage costs used in this analysis are presented in Annex 3. This annex has been 185.
updated since the Third IGCB report to reflect the new formation rate of secondary particles, the latest recommendations from COMEAP on the use of hazard rates and to reflect the removal of indirect effects from ozone for the NOX damage costs. In
addition, the methodology for the derivation of the damage costs is described in detail in an accompanying report (Watkiss et al, 2006). Damage costs are derived from comprehensive modelling analysis, using the impact-pathway approach i.e using the same approach as for those measures being assessed using the full modelling of population weighted concentrations. They are derived from runs that aim to estimate the marginal benefits of emission changes and incorporate the impacts on human health, materials and crops.
The effects included in the damage costs estimates are presented in Table 2.10 186.
below.
Table 2.10: Effects included in damage costs estimates
Burden Effect
Human exposure to PM10/PM2.5
(emitted directly or formed indirectly from NO2 or SO2)
Chronic effects on mortality
Acute effects on morbidity (respiratory and cardiac hospital admissions)
Human exposure to SO2
(emitted directly) Acute effects on mortality and morbidity (respiratory hospital admissions) Exposure of crops to ozone Yield loss for barley, cotton, fruit, grape, hops, millet,
maize, oats, olive, potato, pulses, rapeseed, rice, rye, seed cotton, soybean, sugar beet, sunflower seed, tobacco, wheat
Damage to materials Acidic deposition
Ozone damage to polymeric materials Building soiling
The starting point for the analysis has been the assessment of the baseline conditions, 187.
as described in section 2.4 of this chapter, in 2010. The impacts of the baseline are quantified and valued, using the methodology described in sections 2.5.2 to 2.5.5 above.
The analysis then looks at marginal emissions reductions, reducing the emissions 188.
individually by 10% in each sector, or by a suitable marginal quantity (e.g. 50,000 tonnes). The impact-pathway analysis is re-estimated (changes in emissions, changes in air pollution concentrations, changes in impacts, changes in values) as described in previous sections. The marginal change in values is then divided by the change in emissions (in tonnes) to produce a damage cost. At present it is assumed that the model response to different marginal changes will be linear (i.e. for smaller or larger changes than 10%). This approximation is generally appropriate for primary PM and secondary PM analysis but less so for ozone.
The damage costs aim to reflect the marginal damage costs of pollution, i.e. the 189.
additional marginal effect of one extra tonne of pollution (or the removal of one extra tonne of pollution). Previous studies have shown that the marginal damage costs of air pollution vary very significantly (per tonne of pollutant emitted) according to a range of parameters including:
•
Location of emissions;•
Height of emission;•
Local and regional meteorology and other secondary pollutant precursors; and•
Local and regional receptors (density of receptors and geographical spread).To try and address this, the analysis has used a different approach for different pollutants: 190.
For primary particulates (PM
191. 10), the analysis has produced separate values for each
major sector. This reflects the importance of PM as a local pollutant, and takes into account the stack height and location of emissions (in relation to population density). This is necessary as previous analysis70 has shown that order of magnitude differences can occur for damage costs from PM10 between emissions in different locations from
different sources. In summary, areas of higher population density/local population (urban areas) have higher damage costs, because emissions lead to higher population weighted exposure per tonne;
For secondary pollutants (secondary particulates), one uniform value has been derived 192.
for the UK. This reflects the fact that local issues are less important for these pollutants. These secondary pollutants form in the atmosphere over time, and so the immediate local environment is less important in determining damage costs;
In the analysis for the AQS, the 1 year damage costs have been used. These assume 193.
that the modelled change in concentration occurs for 1 year only, although the impact on life expectancy is followed up for a 100 year period. These annual damage costs 70 ‘An Evaluation of the Air Quality Strategy’ Defra, (2005a).
have been used to value the benefits of the short term measures over the timeframe of the policy (5-15 years, depending on the measure). In applying these per tonne estimates to policy measures, the 2005 values have been uplifted by 2% p.a. in future years to reflect the assumption that willingness to pay increases in line with economic growth. The change in emissions in each year have then been valued using the appropriate annual damage costs.
As with the scenarios that have been modelled on concentration data, all results are 194.
shown as annualised figures.